Ventilator having an oscillatory inspiratory phase and method

ABSTRACT

Quick disconnect assembly comprising a female fitting having a socket formed therein and a male fitting having a bayonet adapted to fit in said socket. Seals are carried by the female and male fittings for forming an airtight seal between the bayonet and the socket. A retainer is provided for retaining said fittings in engagement with each other.

This application is a division of application Ser. No. 145,734 filedJan. 14, 1988, now U.S. Pat. No. 5,007,420 which is a file-wrappercontinuation of a continuation-in-part application Ser. No. 671,491filed on Nov. 14, 1984 now abandoned which is a continuation-in-part ofcontinuation-in-part application Ser. No. 516,133, filed Jul. 21, 1983,now issued as U.S. Pat. No. 4,592,349 on Jun. 3, 1986 which is acontinuation-in-part of application Ser. No. 291,622 filed Aug. 10, 1981now abandoned which is a continuation-in-part of application Ser. Nos.261,929 and 250,586 filed on Apr. 3, 1981, now abandoned.

This invention relates generally to a ventilator and a method and moreparticularly to a ventilator having an oscillatory inspiratory phase andmethod.

Heretofore, ventilators have been provided. However, there has alwaysbeen a need to obtain better distribution of gas volumes throughout thepulmonary structures of the patient to increase the available blood gasinterface. With conventional ventilators, it has become increasinglydifficult to make any substantial improvements in obtaining betterdistribution of gas volumes and therefore there is a need for animproved ventilator and method making this possible.

In general, it is the object of the present invention to provide animproved ventilator and method in which microvolumes of gases can bedelivered to the patient airway.

Another object of the invention is to provide a ventilator and method ofthe above character in which the ventilator gases are delivered inpulsatile form to the patient airway.

Another object of the invention is to provide a ventilator and method ofthe above character in which the pulsatile gases can be deliveredagainst a constant positive airway pressure in the patient airway.

Another object of the invention is to provide a ventilator and method inwhich pulsatile gases can be delivered in a programmed manner.

Another object of the invention is to provide a ventilator and method ofthe above character in which pulsatile gases can be delivered to theairway of the patient under manual control.

Another object of the invention is to provide a ventilator and method ofthe above character in which the pulsatile gases can be supplied to theairway of the patient at automatically timed intervals.

Another object of the invention is to provide a ventilator and method ofthe above character in which tidal volumes of gases can be superimposedupon the pulsatile gases delivered to the airway of the patient.

Another object of the invention is to provide a ventilator and method ofthe above character in which the tidal volumes of gases can be deliveredunder manual or automatic control.

Another object of the invention is to provide a ventilator and method ofthe above character in which it is possible to deliver pulsatile gasesduring the time that tidal volumes of gases are being delivered to theairway of the patient.

Another object of the invention is to provide a ventilator and method ofthe above character in which pulsatile gases with a programmed amplitudecan be supplied to the proximal airway of the patient to produceintrapulmonary mechanical mixing with secondary acceleration ofpulmonary gas diffusion.

Another object of the invention is to provide a ventilator and method ofthe above character in which percussive pulses of gases are supplied tothe physiological cardiopulmonary structures of the patient to maintainmaximum blood/gas interface and cardiac output while mobilizingintrapulmonary secretions with minimal tendency toward pulmonarybarotrauma.

Another object of the invention is to provide a ventilator and method ofthe above character in which the volume of gases delivered to thepatient can be proportioned in accordance with the size of the mammal byincreasing or decreasing source pressures.

Another object of the invention is to provide a ventilator and method ofthe above character in which adequate gases can be supplied to thepatient while lowering the source pressure and changing the frequencyrange proportionally to maintain optimal clinical parameters forfrequency and pressure rise.

Another object of the invention is to provide a ventilator and method ofthe above character in which if failure occurs will fail into a failsafemode with the initiation of an alarm.

Another object of the invention is to provide a ventilator and method ofthe above character which prevents overinflation of the pulmonarystructures of the patient beyond those mechanically programmed.

Another object of the invention is to provide a ventilator and method ofthe above character which accommodates both diffusion and volumeexchange respiration.

Another object of the invention is to provide a ventilator and method ofthe above character in which automatic oxygen enrichment is providedduring an explosive decompression.

Another object of the invention is to provide a ventilator and method ofthe above character in which automatic decompression of the patientairway is provided in the event of an explosive decompression.

Another object of the invention is to provide a ventilator and method ofthe above character in which positive airway pressure is maintainedduring the time that the patient airway is emptied to the atmosphere inthe event of an explosive decompression.

Another object of the invention is to provide a ventilator and method ofthe above character with which can be utilized adjustable sourcepressures to provide higher pressures for larger tidal volumes forvolumetric respiration and lower pressure for higher frequency strokevolume for diffusion respiration.

Another object of the invention is to provide a ventilator and method ofthe above character in which higher stroke volumes are utilized forincreasing arterial oxygen by diffusion.

Another object of the invention is to provide a ventilator and method ofthe above character in which periodic large tidal volumes are suppliedto the patient airway for diluting or washing out the carbon dioxide inthe patient airway.

Another object of the invention is to provide a ventilator and method ofthe above character in which an oscillatory constant positive airwaypressure is maintained for controlling right to left pulmonary shuntsand maintaining an effective respiratory diffusion and volumetricexchange.

Another object of the invention is to provide a ventilator and method ofthe above character in which a minimum amount of dead space is providedwith a maximum stroke volume and a minimal oscillatory constant positiveairway pressure.

Another object of the invention is to provide a ventilator and method ofthe above character in which cyclic oscillatory timing is provided withcapabilities of manual override to permit patient self-treatment tothereby permit phasing so that the patient can expectorate.

Another object of the invention is to provide a ventilator and method ofthe above character in which the termination of ventilation isaccomplished in a gradual manner in order to minimize the possibility ofpatient airway collapse.

Another object of the invention is to provide a ventilator and method ofthe above character which remains in phase at high frequencies.

Another object of the invention is to provide a ventilator of the abovecharacter which is entirely under pneumatic control.

Another object of the invention is to provide a ventilator of the abovecharacter which can operate reliably at high frequencies for longperiods of time.

Another object of the invention is to provide a ventilator and method ofthe above character which can be utilized with infants and adults.

Another object of the invention is to provide a ventilator which ismodular in form.

Another object of the invention is to provide a ventilator of the abovecharacter which can be utilized for ventilating neonates to giants.

Another object of the invention is to provide a ventilator of the abovecharacter in which control is provided over inspiratory time, expiratorytime, inspiratory flow rate, demand CPAP/PEEP and aerosol generation.

Another object of the invention is to provide a ventilator of the abovecharacter in which various I/E ratios can be selected.

Another object of the invention is to provide a ventilator of the abovecharacter in which inspiratory and expiratory times can be varied.

Another object of the invention is to provide a respirator of the abovecharacter in which time cycled expiratory/inspiratory intervals can beprovided.

Another object of the invention is to provide a ventilator of the abovecharacter in which a failsafe governor alert has been provided.

Another object of the invention is to provide a ventilator of the abovecharacter in which a counterpulsing flow is provided.

Another object of the invention is to provide a ventilator of the abovecharacter in which the counterpulsing flow is out of phase with the flowprovided by the timing circuit.

Another object of the invention is to provide a ventilator of the abovecharacter in which constant positive airway pressure can be providedwhile the ventilator is being time cycled.

Another object of the invention is to provide a ventilator of the abovecharacter in which large variations in timing can be obtained.

Another object of the invention is to provide a ventilator of the abovecharacter in which time cycling can be provided with a desiredinspiratory/expiratory ratio.

Another object of the invention is to provide a ventilator of the abovecharacter in which it is possible to adjust the rate of inspiratory flowwhile retaining the capability to vary the inspiratory/expiratory ratio.

Another object of the invention is to provide a ventilator of the abovecharacter in which the frequency can be controlled independent of theinspiratory/expiratory ratio selected.

Another object of the invention is to provide a ventilator of the abovecharacter in which the amplitude can be controlled independent of theselected inspiratory/expiratory ratio.

Another object of the invention is to provide a ventilator of the abovecharacter in which certain components of the ventilator bypass theon/off switch to make certain functions of the ventilator obligatory assoon as source gas is connected to the ventilator.

Another object of the invention is to provide a ventilator of the abovecharacter which has various failsafe features which preventoverpressures being applied to the patient airway.

Another object of the invention is to provide a ventilator of the abovecharacter which prevents a sudden rush of inspiratory gas into theairway of the patient.

Another object of the invention is to provide a ventilator of the abovecharacter which prevents a sudden rush of inspiratory gas being suppliedto the patient even prior to turning on of the on/off switch of theventilator.

Another object of the invention is to provide a ventilator of the abovecharacter in which certain functions are provided before the ventilatoris turned on including demand constant positive airway pressure, manualoverride, nebulization and failsafe operation.

Another object of the invention is to provide a ventilator of the abovecharacter in which a gas leak is provided in the system to prevent alockout of the system.

Another object of the invention is to provide a ventilator of the abovecharacter in which a failsafe exhalation valve assembly is provided inclose proximity to the patient airway.

Another object of the invention is to provide a check valve for use in aventilator which will operate at high frequencies.

Another object of the invention is to provide a check valve of the abovecharacter which does not dance or flutter at high frequencies.

Another object of the invention is to provide a flow/timing cartridgefor use in a ventilator which will operate over a very wide range ofoperational pressures extending from the neo-natal range to the adultrange.

Another object of the invention is to provide a flow/timing cartridgewhich has an extremely long life.

Another object of the invention is to provide a flow/timing cartridgewhich is stable at high frequencies without observable chatter or wobbleof the poppet.

Another object of the invention is to provide a flow/timing cartridge ofthe above character with excellent flow capabilities while maintaining asubstantial pressure drop across the valve gate.

Another object of the invention is to provide a flow/timing cartridge ofthe above character which can be constructed in two sections tofacilitate replacement of a section.

Another object of the invention is to provide an augmented nebulizer foruse in a ventilator of the character described in which the nebulizedoutput is substantially increased.

Another object of the invention is to provide an augmented nebulizer ofthe above character in which the temperature of the nebulized outputgases can be increased.

Another object of the invention is to provide an augmented nebulizer ofthe above character in which the output gases can be heated to apredetermined temperature.

Another object of the invention is to provide a ventilator havingoscillatory demand constant positive airway pressure.

Another object of the invention is to provide a ventilator of the abovecharacter having oscillatory demand CPAP in which the ramping up of thewave form occurs in smaller and smaller stroke volumes until a maximumis reached.

Another object of the invention is to provide a ventilator havingoscillatory demand CPAP in which there is a relatively smooth ramping upof the wave form and a relatively smooth ramping down of the wave form.

Another object of the invention is to provide a ventilator of the abovecharacter in which a substantially sinusoidal wave pattern can beproduced.

Another object of the invention is to provide a ventilator of the abovecharacter in which stable pulsations can be provided over the entirerange of operation of the ventilator.

Another object of the invention is to provide a ventilator of the abovecharacter which remains stable at different altitudes.

Another object of the invention is to provide a ventilator of the abovecharacter in which such stability at various altitudes is obtained byshifting the position of the loading valve with respect to the primaryoscillator cartridge.

Another object of the invention is to provide a ventilator whichincorporate mode switching so that patient care can be programmed to theamount of medical source gas available.

Another object of the invention is to provide a ventilator of the abovecharacter incorporating the present invention which can be utilized withrelatively small volumes of available medical source gas.

Another object of the invention is to provide a ventilator of the abovecharacter which is provided for means for limiting pressure rise in atime cycled pressure variable ventilator.

Additional objects and features of the invention will appear from thefollowing description in which the preferred embodiment is set forth indetail in conjunction with the accompanying drawings.

FIG. 1 is a schematic illustration of a ventilator incorporating thepresent invention.

FIG. 2 is a graph showing the method by which a patient is ventilatedwith the present ventilator.

FIG. 3 is a schematic illustration of another embodiment of a ventilatorincorporating the present invention.

FIG. 4 is a graph showing the method by which a patient is ventilatedwith the ventilator shown in FIG. 3.

FIG. 5 is a schematic diagram of a breathing circuit for use inventilators of the present invention and which incorporates aparticularly novel nebulizer and shrouded venturi assembly.

FIG. 6 is a schematic illustration of still another ventilatorincorporating the present invention.

FIG. 6A is a schematic diagram of an optional oscillator and breathingcircuit for use in the ventilator shown in FIG. 6.

FIG. 6B is a schematic illustration of a breathing circuit utilizing asub-ambient venturi for the exhalation valve assembly for use in theventilator shown in FIG. 6.

FIG. 7 is a schematic illustration of still another ventilatorincorporating the present invention.

FIG. 7A is a schematic diagram of an optical circuit for use in theventilator shown in FIG. 7.

FIG. 8 is a schematic illustration of a decompression and expiratoryoscillation module for use in a ventilator of the type shown in FIG. 3.

FIG. 9 is a schematic illustration of an automatic aneroid decompressionrelief valve assembly adapted to be used in a ventilator of the typeshown in FIG. 3.

FIG. 10 is a cross sectional view of a combination venturi assembly andexhalation valve assembly which can be utilized in the ventilator of thepresent invention.

FIG. 11 is a schematic illustration of a breathing circuit for use withthe ventilators of the present invention.

FIG. 12 is a side elevational view of a quick-disconnect fitting for usein ventilators of the present invention.

FIG. 13 is a cross sectional view taken along the line 13--13 of FIG.12.

FIG. 14 is a side elevational view of another embodiment of a quickdisconnect fitting for use in ventilators of the present invention.

FIG. 15 is a cross sectional view taken along the line 15--15 of FIG.14.

FIG. 16 is a perspective view of a ventilator incorporating the presentinvention being utilized by a patient.

FIG. 17 is a view of the ventilator shown in FIG. 16 but showing thecompartment door in an open position and showing the handle supportingthe ventilator so that the front panel is inclined.

FIG. 18 is a schematic circuit of the pneumatic circuitry utilized inthe invention shown in FIG. 17.

FIG. 19 is a cross sectional view of a flow obtunder used in thecircuitry shown in FIG. 18.

FIG. 20 is a side elevational view of a nebulizer incorporating thepresent invention.

FIG. 21 is a cross sectional view of a portion of the nebulizer shown inFIG. 20.

FIG. 22 is still another embodiment of a ventilator incorporating thepresent invention and showing the same mounted upon a stand so that itcan be wheeled from one location to another.

FIG. 23 is a schematic diagram of the pneumatic circuitry ventilatorshown in FIG. 22.

FIG. 24 is a graph showing the performance of the ventilator shown inFIG. 22 and 23.

FIG. 25 is still another embodiment of a ventilator incorporating thepresent invention.

FIG. 26 is a schematic diagram of the pneumatic circuitry utilized inthe ventilator shown in FIG. 25.

FIG. 27 is a cross sectional exploded view of the nebulizer utilized inthe ventilator in FIG. 25.

FIG. 28 is a cross sectional view of the combination venturi jet andexhalation valve assembly used in the ventilator in FIG. 25.

FIG. 29 is an isometric view of a portion of the breathing apparatusconnected to the ventilator in FIG. 25.

FIG. 30 is a cross sectional view of a governor alert incorporating thepresent invention and used in the ventilator in FIG. 25.

FIG. 31 is a view of a dual combination venturi jet and exhalation valveassembly with certain portions broken away.

FIGS. 32 through 34 are graphs showing the performance of the ventilatorshown in FIG. 25.

FIG. 35 is an enlarged cross-sectional view of a modified sleeve checkvalve.

FIG. 36 is an enlarged cross-sectional view taken along the line 36--36of FIG. 35.

FIG. 37 is a side elevational view partially in cross section of aflow/timing cartridge incorporating the present invention and for use ina ventilator.

FIG. 38 is a cross sectional view taken along the line 38--38 of FIG.37.

FIG. 39 is a cross sectional view, also partly in cross section of aflow/timing cartridge incorporating the present invention for use in aventilator and similar to the flow timing cartridge shown in FIGS. 37and 38 but differing in that it is formed in two sections which may beremovably detached from each other.

FIG. 40 is a cross sectional view taken along the line 40--40 of FIG.39.

FIG. 41 is a cross sectional view, partially in schematic form of anaugmented nebulizer incorporating the present invention for use in aventilator and having auxiliary heating means.

FIG. 42 is a schematic diagram of an enhancement metering circuit whichcan be utilized in the circuit shown in FIG. 26 to provide oscillatorydemand CPAP.

FIG. 43 is a wave form obtained from the circuitry shown in FIG. 42 andproviding an oscillatory demand CPAP.

FIG. 44 is a graph produced from the ventilator shown in FIG. 42 and inwhich a sinusoidal oscillator demand CPAP is obtained.

FIG. 45 is a partial schematic view of the ventilator shown in FIG. 26showing the manner in which the loading valve position has been changedwith respect to the primary oscillator cartridge to obtain ventilatorstability at different altitudes.

FIG. 46 is a schematic diagram of the mode switching arrangement for usewith ventilators of the present invention.

In FIG. 1, there is shown a schematic diagram of a ventilator having anoscillatory inspiratory phase which as shown consists generally of apower control module 11, an oscillatory diffusion module 12, a transportservice module 13, an oscillatory volumetric ventilator module with CPAPand alarm-failsafe 14, and a universal breathing circuit 16.

The power control module 11 consists of an oxygen blender 21 ofconventional type such as that described in U.S. Pat. No. 3,727,627. Theoxygen blender 21 is provided with inlet ports 22 and 23 with inlet port22 being connected to a suitable source of gas such as air underpressure and port 23 being connected to another source of gas as, forexample, oxygen under pressure. The blender 21 is provided with acontrol knob 25 to permit the adjustment of the ratio of air to oxygen.The blender 21 is provided with additional ports 24, 26 and 27. The port24 is connected to port 27. The port 24 is also connected to the outletport 31 of a normally closed bypass cartridge 32. The bypass cartridge32 is adapted to be moved to an open position by gas being supplied to aservo port 33 of the bypass cartridge 32. The bypass cartridge 32 isalso provided with an inlet port 34 which is connected through isolationcheck valves 36 and 37 connected respectively to the inlet ports 22 and23 and to the sources of air and oxygen as shown.

The outlet 26 from the blender 21 typically is an outlet which providesan alarm when there is inadequate or single gas available to the blender21. As pointed out herebefore, this outlet 26 is connected to the inletport 33 of the bypass cartridge 32 so that in the event there isinsufficient gas flow through the blender 21, the bypass cartridge 32 isactuated to move it to an open position to permit gas to flow eitherfrom the sources of air or oxygen through the isolation valves 36 and 37through the inlet port 34 and through the outlet port 31 to the outletport 24 of the blender 21.

Means is provided for giving an indication as to when the bypasscartridge is actuated to cause bypassing of the blender 21 and consistsof an adjustable bypass indicator calibration valve 38 which isconnected to the inlet port 33 of the bypass cartridge 32. Thecalibration valve 38 is also connected to a bypass indicator 39 of aconventional type such as a "Rotowink" light which is a light whichchanges color from a normal black to a red during the time that thebypass cartridge is bypassing gas. The valve 38 is also connected to afixed bleed orifice 41 which is open to ambient. For example, it canhave a suitable size such as 0.013 of an inch and is utilized to preventan overpressure from occurring. If desired, the bleed orifice can beconnected to a suitable audible alarm, as for example a whistle.

Gas from the power control module 11 from the outlet 24 of the blender21 is supplied to the transport service module 13 to inlet 44 of anadjustable system pressure regulator 46. The system pressure regulator46 is utilized for reducing the line pressure from above fifty poundsdown to approximately fifty psi. The gas supplied from the power controlmodule 11 in addition to being supplied to the inlet 44 of the pressureregulator 46 is also supplied to an aspirator power socket 47 of thetransport service module 13. Gas is also delivered to the inlet port 48of a demand CPAP cartridge 49.

Unregulated gas is also supplied from the inlet port 44 of the regulator46 to the inlet port 51 of an adjustable nebulizer control valve 52 ofthe oscillatory diffusion module 12. Metered gas is then supplied fromthe valve 52 through its outlet port 53 to a nebulizer service socket54. A fitting 56 is mounted in the service socket 54 and is connected toan inlet port 57 of a nebulizer 58. The nebulizer 58 can be of the typedescribed in U.S. Pat. No. 3,353,536. In addition, unregulated gas issupplied from a line connected to the inlet 44 of the regulator 46 tothe inlet 61 of another adjustable reservoir control needle valve 62.The outlet port 63 of the needle valve 62 is connected to a reservoirservice socket 64. A fitting 66 is mounted in the service socket 64 andis connected to an inlet port 67 of an entrainment gate 68 which isconnected to an entrainment reservoir 69. Thus it can be seen thatunregulated mixed gases of the appropriate type are supplied to theaspirator power socket 47, to the inlet of the demand CPAP cartridge 48and to the inlets of the nebulizer control metering valve 52 and thereservoir control valve 62.

With respect to gas which is supplied through the regulator 46, suchregulated gas is supplied from an outlet 70 through an adjustableorifice 71 to a gauge 72 which registers the regulated pressure which issupplied from the regulator 46. The orifice 71 minimizes the effect offluctuating pressures on the gauge 72. Regulated gas is also supplied tothe inlet 73 of a manual inspiration valve 74. The manual inspirationvalve 74 is provided with a push button 76 which when actuated placesthe ventilator in an inspiratory phase as hereinafter described andsupplies regulated gas through its outlet port 77 to an inlet port 78 ofa normally open failsafe cartridge 79. The gas flows from the inlet port78 through an outlet port 81 to a venturi service socket 82. A fitting83 is mounted in the service socket 82 and is connected to a jet ornozzle 84. An inlet port 86 of the normally open failsafe cartridge 79is connected to an outlet port 87 of an interrupter cartridge 88.

The transport service module 13 also includes a gauge 89 which isutilized for measuring the vacuum which is established duringaspiration. The gauge 89 is connected to aspirator monitor servicesocket 90. This aspirator service socket can receive a fitting which canbe utilized to monitor the aspirator pressure which is being generated.The outlet port 47 of the regulator 46 is also connected to the inletport 91 of a rotary on/off master switch 92 in the oscillatory diffusionmodule 12. The outlet 93 of the switch 92 is connected through a timingisolation check valve 94 to an inlet port 96 of a sealed aneroid timingregulator 97 forming a part of the transport service module 13. Thisregulator 97 is set at a lower pressure than the regulator 46 as, forexample, 30 psi. The regulator 97 is provided with a sealed referencegas as, for example, a reference which will provide an output of 30 psi.This constant pressure of 30 psi is used in the master timing circuit ashereinafter described so that the timing is not changed in the event ofan explosive decompression. The outlet port 98 of the regulator 97 isconnected to an inlet port 99 on a timing cartridge 101.

The transport service module 13 also includes another gauge 102 which isprovided for measuring the pressure in the patient's airway. This gaugeis connected to an adjustable orifice 103 which is connected to aservice socket 104. A fitting 106 is provided in the service socket andis connected to a port 107 of an encapsulated venturi assembly 108. Inthis way, the pressure in the proximal airway breathing circuit for thepatient is measured. This airway pressure which is being monitored issupplied from the socket 104 to an inlet port 109 of the demand CPAPcartridge 49. This gas is also supplied to an adjustable metering valve111 which is provided for CPAP dampening. The outlet of the meteringvalve 111 is connected to an outlet port 112 of the demand CPAPcartridge 49. The outlet is also connected to a one way check valve 113to the inlet port 78 of the failsafe cartridge 79. The connectionbetween the needle valve 111 and the outlet port 112 serves to stabilizethe operation of the demand CPAP cartridge.

Now with respect to the oscillatory diffusion module 12, regulated gaswhich is supplied from the regulator 46 through the rotary on/off switch92 is supplied through the timing isolation check valve 94 to an inletport 116 of a normally open automatic nebulization cartridge 117.

In the oscillatory diffusion module, the outlet port 93 of the rotarymaster switch 92 is connected to an oscillator reservoir 121 which isutilized for smoothing out the operational pressures. The oscillatorreservoir 121 is connected to an inlet port 122 of an oscillatorcartridge 123. The oscillator reservoir 121 is also connected to theinlet port 124 of an autoload cartridge 126. Gas is also supplied to oneside of the reset check valve 127 and to a loading orifice 128 of asuitable size such as 0.013 of an inch to the servo port 129 of theautoload cartridge 126. A loading reservoir 130 is connected between theservo port 129 of the autoload cartridge 126 and the reset check valve127. The autoload cartridge 126 is a normally open cartridge and gassupplied to the inlet port 124 travels through an outlet port 131. Gasis supplied from the outlet port 131 to one side of a ramping isolationcheck valve 132 and to a servo port 133 of a normally open interruptercartridge 88. The cartridge 88 is provided with an inlet port 134. Gasis also supplied from the outlet port 131 to one side of a servoisolation check valve 135.

The oscillator cartridge 123 is provided with an outlet port 136connected to the inlet port 134 of the interrupter cartridge 88 and toone side of an oscillatory control isolation check valve 137. The otherside of the check valve 137 is connected to an inlet port 138 of aninspiratory metering valve 139. The inspiratory metering valve 139 isprovided with an outlet port 141 which is connected to an inlet port 142of an expiratory metering valve 143. The inspiratory metering valve 139is provided with an outlet port 144 connected to a servo port 146 of theoscillator cartridge 123. The expiratory metering valve 143 is providedwith an outlet port 147 connected to the reservoir service socket 64 andthence into the bag-like entrainment reservoir 69.

When the interrupter cartridge 88 is open, gas flows from the outletport 87 of the interrupter cartridge to an inlet port 151 of anadjustable metering valve 152 which meters gas into a servo port 153 ofa failsafe servo cartridge 154 and to an anti-surge pressure balancereservoir 155 which is connected to one side of an alarm reset checkvalve 156. Gas in addition to being supplied to the inlet port 151 issupplied to the other side of the alarm reset check valve 156 and alsoto an inlet port 157 of the failsafe servo cartridge 154. The failsafeservo cartridge 154 is a normally closed cartridge and when gas suppliedto the servo port 153, the cartridge is moved to the open position andgas flows through an outlet port 158 and is supplied to a failsafeindicator 159 and to a servo port 161 of the normally open failsafecartridge 79. At the same time that gas is supplied to the servo port161, it is also supplied to the inlet port 162 of a failsafe alarmcalibration metering valve 163. The gas from the outlet port 164 of themetering valve 163 is supplied to an alarm isolation check valve 166which is connected to an audible whistle alarm 167. The outlet port 164is also connected to an alarm balance orifice 168 of a suitable size as,for example, 0.024 inches and is connected to the entrainment reservoir69. If the tubing leading to reservoir 69 is overfilled, or in otherwords overwhelmed, gas will pass in a reverse direction through thealarm balance orifice 168 through the check valve 166 and into the alarm167 to sound an alarm.

Once an alarm sounds, it is necessary to provide some means forresetting the failsafe servo. This is accomplished by the use of anormally closed failsafe reset pushbutton 171 which is connected to anoutlet port 172 of the adjustable metering valve 152. When thepushbutton 171 is operated, gas is dumped from behind the diaphragm inthe failsafe servo cartridge 154 permitting the failsafe servo cartridgeto return to its normally closed position. This will permit the systemto start operating again. The amount of pressure which is required foropening the failsafe servo cartridge can be adjusted by rotation of theknob 173 of the cartridge 154.

In the oscillatory diffusion module 12, the timing cartridge 101 isprovided with an outlet port 176 which is connected to a timing manifold177. The timing manifold 177 is connected to one side of the rampingisolation check valve 132. It is also connected to one side of anadjustable ramping orifice 178 which is connected to the servo port 133of the interrupter cartridge 88. One side of the ramping isolation checkvalve 132 is connected to the servo port 133 and thus gas supplied fromthe timing manifold 177 rapidly servos the interrupter cartridge 88 to aclosed position from its normally open position. Gas introduced into theinterrupter cartridge 88 causing it to servo into the closed positionwill be gradually bled off through the ramping orifice 178 to create aslow opening of the interrupter cartridge to prevent stalling of theoscillator by dropping servoing pressure too rapidly. Gas bleeding fromthe interrupter cartridge bleeds through the ramping orifice 178 andback into the timing manifold 177 which would be depressurized by thistime.

The manifold 177 is also connected to a reservoir refill orifice 179 ofsuitable size such as 0.024 inches. The other side of the orifice 179 isconnected to the reservoir 69. The timing manifold 177 is also connectedto the servo ports 181 of the automatic nebulization cartridge 117 andalso to the servo port 182 of the timing reset cartridge 183. The timingmanifold 177 is also connected to a timing isolation check valve 184which is connected to a volumetric exchange or exhalation metering valve186. The metering valve 186 is connected to a timing reservoir 187. Thetiming reservoir 187 is connected to a servo port 188 of the timingcartridge 101.

As hereinafter explained, when the timing cartridge 101 is servoed fromits normally open position to a closed position, it will again open foran appropriate period of time as determined by the bleed down through adiffusion interval adjustable metering valve 189 which is connected tothe inlet port 191 of the timing reset cartridge 183. Gas passing intothe inlet port 191 passes through an outlet port 192 and into thereservoir 69.

The automatic nebulization cartridge 117 is provided with an outlet port193 which is connected to a fixed nebulizer orifice of a suitable sizesuch as 0.024 inches. The orifice 194 is connected to the nebulizerservice socket 54 which is connected to the nebulizer 58 as hereinbeforedescribed.

Now turning to the oscillatory volumetric ventilator module 14, theinlet port 48 of the demand CPAP cartridge 49 is connected to a sourceisolation check valve 196 through which gas passes and is supplied to astabilization reservoir 197. The stabilization reservoir 197 isconnected to the inlet port 198 of a time cycled on/off switch 199 of arotary type. The outlet port 201 of the switch 199 is connected to aninlet port 202 of a normally closed inspiratory time cartridge 203. Gasis also supplied to an inlet port 204 of a normally open expiratory timecartridge 206. The cartridge 203 is provided with an adjustable spring205 for biasing the opening of cartridge 203. Gas from the inlet port204 of cartridge 206 normally flows through the cartridge through anoutlet port 207 to one side of an inspiratory isolation check valve 208which is connected to an adjustable metering valve 209. The meteringvalve 209 is connected to the servo port 211 of the inspiratory timecartridge 203. The metering valve 209 is also connected to theentrainment reservoir 69. The outlet port 213 of the inspiratory timingcartridge 203 is connected to an adjustable flow pressure metering valve214. The metering valve is connected to a ventilator output low pressurecheck valve 215. The check valve 215 is connected to the check valve113. The metering valve 214 is also connected to one side of aninspiratory isolation check valve 216. The check valve 216 is connectedto an inlet port 217 of an adjustable metering valve 218. The meteringvalve 218 is connected to a servo port 219 of the expiratory timecartridge 206. The metering valve 218 is also connected to theentrainment reservoir 69 in the same manner as the metering valve 209.

In the universal breathing circuit 16, a generally cylindrical body 221is provided which has formed therein a restricted venturi-likepassageway 122. The nozzle or jet 84 is disposed so that the gasesjetting therefrom travel axially of the venturi-like passageway 222. Anadditional cylindrical body 223 is provided which encircles the body 221and forms space 224 between the body 223 and the body 221. The inletport 107 is formed in the body 223 and is utilized for introducing gasesinto the annular space 224 provided between the bodies 221 and 223. Oneend of the body 223 is closed whereas the other end opens into thepatient's airway represented by the balloon-like configuration 226. Thebody 221 is provided with an expiratory gate 227. The body 223 hasconnected thereto an exhalation valve assembly 228. The valve assembly228 is provided with a servo port 229 which is connected to the nozzleinlet 84. The servo port 229 is also connected to a phasing orifice 231,which is open to ambient.

The demand CPAP cartridge 49 is provided with an adjustment knob 244 foradjusting the pressure on a spring 242 for varying the opening pressurerequired for the cartridge 49.

Operation of the ventilator as shown in FIG. 1 incoming gases such asoxygen and air are delivered from the source of gas to the oxygenblender 21 in the power control module 11. A flow of mixed gases isdelivered at the outlet 24. When insufficient gas is being delivered bythe blender 21, the blender 21 will bypass the flow of gas from theoutlet port 24 to the port 27 and thence through the outlet port 26 tointroduce gas into the servo inlet 33 of the bypass cartridge 32 causingit to open and to permit a flow of one of the gases, either air oroxygen through the bypass cartridge and out the outlet port 31 and intothe lines or circuits downstream of the blender 21. Generally a flow ofgas around the components of the blender 21 will occur when one of thetwo gas sources becomes unreliable or is exhausted. The isolation valves36 and 37 prevent backflow between the oxygen and air inlets from thesources of gas.

When gas is being bypassed by the blender, a visible indication is givenby metering gases through the metering valve 38 and supplying the sameto the bypass indicator 39. Gas is also supplied to a bleed off orifice41 which can be supplied to an audible alarm if desired.

The gas which is supplied from the power control module is supplied tothe transport service module 13 to the regulator 46. The pressureregulator 46 provides a means for establishing an optimal pressure for astable oscillatory frequency control with the optimal pressure beingnormally from 45 to 55 psi.

Regulated gas under pressure from the regulator 46 is supplied to themaster oscillator on-off switch 92 forming a part of the oscillatorydiffusion module 12. As soon as the master switch 92 is turned on,regulated gas under pressure is delivered through outlet port 93 to thereservoir 121 and to the inlet port 122 of the oscillator cartridge 123.The oscillator cartridge 123 is normally open with a pneumatic openingand closing differential. Regulated gas is delivered from the oscillatorreservoir 121 which serves as a surge/stabilizer to the oscillatorcartridge 123 which is normally open and gas is delivered through theoutlet port 136 to the inlet of the oscillator frequency inspiratory(flow on) valve 139 through the oscillator control isolation check valve137.

Also when the oscillator on-off switch 92 is turned on, regulated gas inaddition to being supplied to the oscillator cartridge 123 is alsosupplied to the inlet port 124 of the autoload cartridge 126. Regulatedgas is also delivered against the outlet of the reset check valve 127and to the inlet of the loading orifice 128. As soon as gas is suppliedto the inlet port 124 of the autoload cartridge 126, gas flows throughthe normally open autoload cartridge 126 through the outlet port 131 anddirectly loads the diaphragm of the interrupter cartridge 88 through theservo port 133 and provides substantially instantaneous closing of theinterrupter cartridge 88. This prevents a surge of gas through theoscillator cartridge 123 into the circuit connected to the main venturinozzle 84 negating a potential oscillator stall and a large strokevolume at the physiological airway. The loading orifice 128 for theautoload cartridge 126 is sufficiently restrictive so as to allow a twoto three second servoing time before passing sufficient gas to the servoport 129 to servo the autoload diaphragm to the off position. Therefore,it can be seen that the autoload cartridge 126 servos the interruptercartridge 88 closed when the master switch 92 is rotated to the "on"position. The oscillator cartridge 123 remains in the expiratory phaseuntil the timing circuit associated with the interrupter cartridge 88enters its programmed diffusion (inspiratory) phase with the normalramping function. The autoload cartridge 126 remains closed until thesource of gas pressure supplied to it through the master on-off switch92 is turned off. At that time, servoing gases are then dumped from theautoload cartridge 126 out through the reset check valve 127 to permitthe autoload cartridge to return to its normally open position.

At the time that the master on/of switch 92 is turned on, regulated gasis also delivered through the timing isolation check valve 94 to thetiming regulator 97 which as hereinbefore explained, delivers gas at acontrolled pressure as, for example, at 30 psi. This regulator is usedto prevent a surge in case of an explosive decompression as, forexample, if the ventilator is aboard an airborne vehicle during such anevent. Gas under 30 psi pressure is delivered from the outlet 98 intothe inlet port 99 of the timing cartridge 101. The timing cartridge 101is normally open and therefore when gas is delivered into the inlet port99, gas is delivered to the outlet port 176 to the timing manifold 177.When the regulated gas of 30 psi is delivered into the timing manifold177, 30 psi timing gases are distributed to a number of locations.Timing gas is delivered to the servo port 181 of the automaticnebulization cartridge 117. Timing gas is also delivered to the servoport 182 of the timing reset cartridge 183. Timing gas is also deliveredto the ramping circuit for the interrupter cartridge 88 which includesthe ramping isolation check valve 132 and the ramping orifice 178.Timing gas is also supplied from the timing manifold 177 to adiffusion-volumetric exchange timing circuit which includes the timingisolation check valve 184, the volumetric exchange valve 186 and thediffusion interval valve 189. Timing gas travels through the timingisolation check valve 184 and the valves 186 and 189 to the inlet port191 of the timing reset cartridge 183. Timing gas is also delivered tothe reservoir refill bleed orifice 179.

It should be appreciated that when the master switch 92 is rotated tothe one position, the ramping circuit for the interrupter cartridge 88is charged by the autoload cartridge slightly ahead of flow into themaster timing circuit from the timing cartridge 101.

As the master timing circuit is pressurized from the timing manifold177, the normally open automatic nebulization cartridge 117 is servoedclosed by the entrance of timing gas through the servo port 181.Similarly, the normally open timing reset cartridge 183 is servoedclosed through the entrance of gas through its servo port 182. Theramping circuit for the interrupter cartridge 88 is serviced byintroducing timing gas flow against the ramping orifice 178 and to theinlet of the ramping isolation check valve 132. Timing gas enters thediffusion-volumetric exchange interval timing circuit through the timingisolation valve 184 and reservoir refill gas is delivered by the timingcartridge 101 through the fixed timing reservoir refill orifice 179.

Timing gas continues to flow through the master timing circuit from thetiming manifold 177 through the timing isolation check valve 184 andthrough the valve 186 which provides a metered flow of gas that issupplied to the diffusion interval valve 189 which provides a furthermetered gas flow to the inlet port 191 of the timing reset cartridge183. Metered gas from the valve 186 is also supplied through the timingreservoir 187 and into the servo port 188 of the timing cartridge 101.The timing cartridge 101 is normally open and when the pressure behindthe diaphragm rises beyond a yield point the timing cartridge 101 ismoved to a closed position which instantaneously interrupts the flow ofgas into the master timing circuit. The inspiratory phase commences atthis point which also can be characterized as a phasic sequencing of thediffusion interval. The diffusion interval (inspiratory phase) isinitiated by depressurization of the master timing circuit through thefixed timing reservoir refill orifice 179 which bleeds the gas from themaster timing circuit into the reservoir 69. The exact timing of theinspiratory phase of the diffusion interval starts when the timing resetcartridge 183 opens after the gas from behind the diaphragm has bleddown sufficiently through the manifold 177 and through the reservoirrefill orifice 179. The opening of the timing reset cartridge 183permits gas to bleed down from the diffusion interval valve 189 throughthe timing reset cartridge 183 into the entrainment reservoir 69. Thelength of the inspiratory phase or diffusion interval is determined bythe size of the orifice in the volumetric exchange valve 186.

Thus, it can be seen that the servoing gases which are produced by theloading and unloading of the timing cartridge 101 pass throughindependent irreversible pathways to provide infiniteinspiratory-expiratory ratios with the times for the inspiratory andexpiratory phases being determined by the position of the adjustablevalves 186 and 189.

Other than the control provided by the timing cartridge 101, manualinitiation of the inspiratory phase can be accomplished by operating themanual inspiration push button 76. When this is accomplished regulatedgas is delivered from the regulator 46 through the manual inspirationvalve 74 to the inlet port 78 of the failsafe cartridge 79 which isnormally open and permits regulated gas to be delivered through itsoutlet port 81 to the nozzle 84 to deliver gas into the mainventuri-like passageway 122 and into the airway of the patient. Byoperation of the manual inspiration valve 74, it is possible to handpace the inspiratory circuit provides means for manually inflating thelungs of a patient through pressure regulated circuitry associated withthe failsafe servo cartridge 154. Because of this feature, the peakdelivery pressure of the gases supplied to the patient will not exceedthat programmed for oscillatory delivery. Thus, there is provided animportant safety factor for the patient. By operation of the manualinspiration valve 74, it is possible to hand pace the inspiratory andexpiratory phases.

The master timing means hereinbefore described controls the opening andclosing of the interrupter cartridge 88. Because the pressuresdownstream of the oscillator cartridge 123 are too low to operate apneumatic timing circuit, an independent timing circuit has been createdand servoed by a normally open timing cartridge 101.

It can be seen that the periodic master timing circuit hereinbeforedescribed provides programmable means for infiniteinspiratory-expiratory ratios, or volume exchange ratios. Closing thediffusion interval metering valve 189 will produce an infiniteoscillatory interval while closing the volumetric exchange meteringvalve 186 will produce an infinite non-oscillatory interval. Whichevervalve is closed first will command.

Regulated oscillatory gases are supplied by the oscillator cartridge 123and its associated timing circuitry. Oscillation of the oscillatorcartridge 123 is a function of the intermittent loading of theoscillator timing circuit. The normally open oscillator cartridge 123delivers gas to the interrupter cartridge 88 from the outlet port 136 ofthe oscillator cartridge 123 to the inlet port 134 of the interruptercartridge 88. As pressure rises in port 134, flow is introduced throughthe oscillator control check valve 137 into the inlet port 138 of themanifold of the metering valve 139 so that unmetered gas is deliveredthrough the outlet port 141 to the inlet port 142 of the valve 143.Metered gas is delivered from outlet port 144 of the metering valve 139to the servo port 146 of the oscillator cartridge 123. When pressurerises sufficiently in the servo port of the oscillator cartridge 123 as,for example, to approximately 20 psi, the diaphragm of the oscillatorcartridge will cause movement of the valve member to interrupt the flowof regulated gas through the oscillator cartridge 123 to the interruptercartridge 88. When the servoing pressure within the oscillator cartridge123 drops below a predetermined pressure as, for example, 10 psi thevalve member of the oscillator cartridge will again open.

The oscillator cartridge has approximately a 10 psi opening and closingdifferential which serves as an air cam during rapid oscillation foreffective translatory opening and closing. Stroke volume is increased bya more complete opening and closing travel of the valve member in theoscillator cartridge 123 in the time permitted. This is particularlyimportant for maximum amplitude (stroke volume) at each frequency. Theopening and closing differential is accommodated by the difference inpiston effect between the closed (end of the poppet valve only) and openpositions (a much larger area of the diaphragm).

The oscillatory frequency is a factor of the inspiratory/expiratoryratio during oscillation of the gate valve member or poppet that is inthe oscillator cartridge 123. The metering valve 139 determines the timerequired to servo the diaphragm off by metering flow to the servoingdiaphragm. The flow of gas through the metering valve 143 determines thebleed down rate of the diaphragmatic servoing pressure and determineshow long the oscillator cartridge gate valve remains closed.

Oscillator stall (open oscillator cartridge without cycling) iseliminated by the ambient venting of servo gases through the meteringvalve 143 during the period when the interrupter cartridge is closed.This in effect creates a "pneumatic clock" during idle with the rate ofoscillator cartridge opening and closing (oscillation) being determinedby the position of the inspiratory and expiratory metering valves 139and 143.

The oscillator control isolation check valve 137 in conjunction with theoscillator loading circuit venting it through the metering valve 143stabilizes the oscillatory frequency and enhances oscillator strokevolume. The oscillator control isolation check valve 137 has an openingpressure of approximately 3 psi providing a positive initial openingpressure and directing diaphragmatic bleed down through the meteringvalve 143.

During the time that the diaphragm on the oscillator cartridge 123 isbeing loaded, the servoing gases which are passing through theoscillation control or isolation check valve 137 pass through the valve139 and overwhelm the metering orifice of the inspiratory metering valve143 while at the same time loading the diaphragm with metered gasthrough the inspiratory metering valve 139. In this connection, itshould be appreciated that the diaphragmatic loading pressure gradientis substantially higher than the bleed down gradient. Thischaracteristic limits high oscillatory rates. By overwhelming themetering orifice of the valve 143 during the diaphragmatic loading ofthe oscillator cartridge 123, the effective loading pressure required isreduced, thereby lengthening the inspiratory time. However, with theadjustable valves 139 and 143 which are provided, mandatory positiveinspiratory/expiratory ratio is mandated during all expiratory flow.Metering valve 143 can be of a smaller adjustable caliber valve than theinspiratory flow on metering valve 139 to create a more positiveinspiratory/expiratory ratio to reduce a physiological constant positiveairway pressure (CPAP) by lengthening the period of oscillator flow offtime.

As oscillatory frequencies are reduced below 100 cycles per minute tovolumetric ventilation, positive inspiratory/expiratory ratios areincreased as the metering orifice caliber becomes smaller than theexpiratory metering orifice. For example, the expiratory orificeprovided by the valve 143 becomes ineffective and theinspiratory/expiratory ratio is under the control of the inspiratorymetering orifice. As the phasic frequency is reduced, theinspiratory/expiratory ratio becomes more positive, e.g.: 1.4 to 1.5 atslow rates with ever-increasing stroke volumes. Thus, it can be seenthat the oscillatory timing circuit associated with the oscillatorcartridge 123 provides a means for stabilizing oscillatory function aswell as to prevent the clinician or operator from establishing aconflicting clinical program beyond normal physiological limits of thepatient over a wide range of oscillatory frequencies.

The oscillator timing circuit associated with the oscillator cartridge123 in conjunction with an opening and closing differential enables awide range of oscillatory frequencies. As the regulated gases enter thenormally open oscillator cartridge 123, they are delivered into thenormally open interrupter cartridge 88 and then caused to flow against adownstream resistance with oscillatory operational pressures averagingfive to fifteen psi which is in comparison to the 35 to 50 psioperational pressures in conventional timing circuits. The oscillatorreservoir 121 increases stroke volume by creating a more positive valveopening with a larger metering orifice at a given frequency. Theinspiratory/expiratory ratio control which is provided allows for a morecontrolled bleeddown of the oscillator timing circuit affecting bothrate and stroke volume. During loading, the means servoing pressure ishigher. During (depressurization) unloading gases flow through bothmetering valves 139 and 143 creating a depressurization under lower meanpressure gradients, thus decreasing oscillatory frequency and modifyingresidual systemic pressures.

Thus, it can be seen that the oscillator 123 with its timing circuitwill deliver regulated gases at a pulse rate determined by theoscillator preprogrammed frequency. The outflow from the interruptercartridge 88 from the outlet port 87 is delivered to the inlet port 86of the normally open failsafe cartridge 79. Oscillatory gases aredelivered from the outlet port 81 of the failsafe cartridge 79 to theventuri service socket 82 and through the nozzle 84 into the mainventuri-like passageway into the patient's airway 226.

The interrupter cartridge 88 provides a means for controlling thediffusion interval and allows volumetric diffusion respiration to occurby programming periodic oscillation.

Locating the interrupter cartridge 88 downstream from the oscillatorcartridge 123 provides antisurge protection which would not be presentif the interrupter cartridge were located upstream of the oscillatorcartridge 123.

It has been found that if interrupter cartridge 88 is opened toorapidly, an oscillator stall can occur because the loading pressures atthe inlet port 134 will drop below critical oscillator diaphragmservoing levels. The ramping circuit which has been provided for theinterrupter cartridge 88 prevents oscillator stall and creates a softstart of oscillation and causing a gradual oscillatory increase instroke volume at the physiological airway of the patient.

As pointed out previously, timing gases are delivered to a rampingisolation check valve 132 and to the metering valve 178. During the timethat the diaphragm of the interrupter cartridge 88 is being loadedthrough the servo port 133, timing gases are allowed to surge into thecircuit for rapid closing of the interrupter cartridge 88. Duringopening of the interrupter cartridge 88, bleed down of gases from thediaphragm is metered through the adjustable ramping metering valve 178to retard the opening of the interrupter cartridge 88 and to provide a"gentle" opening which obtunds oscillatory amplitude during thetransitional opening.

The interrupter cartridge 88 can be servoed closed by gases from theautoload cartridge 126 as hereinbefore described. It also can be servoedclosed by pressurization from the interrupter (master) timing circuit.

Thus, it can be seen that when the master on/off switch 92 is turned onthe interrupter cartridge 88 will be servoed into a closed position bythe autoload cartridge 126 and will open softly to permit regulatedoscillatory gases to be supplied by the oscillator cartridge 123 throughthe interrupter cartridge which is opened gently under the control ofthe timing circuitry hereinbefore described to deliver gases to thepatient airway which during the inspiratory phase will supply pulses ofgas under pressure to provide an oscillatory ramping pressure rise asdepicted in the curves shown in FIG. 2 and as hereinafter described morein detail.

The oscillatory diffusion module 12 supplies gases to three sockets, theventuri power socket 82, the nebulizer power socket 54, and thereservoir power socket 64. All of the programmed inspiratory gases aredelivered through the venturi socket 82. The nebulizer power socket 56delivers automatic regulated gases and manually controlled non-regulatedgases.

The automatic nebulization cartridge 117 receives regulated gasdownstream from the timing isolation check valve 94 from which it isapplied to the input port 116. The nebulizer cartridge 117 is servoed toan open position just immediately prior to the time the ventilatorenters the inspiratory phase or diffusion interval and delivers sourcegas from the outlet port 193 to the inlet of the fixed nebulizer orifice194. The fixed nebulizer orifice 194 meters gas for driving thenebulizer/humidifier 58 by supplying such gases to the nebulizer socket54 and supplying the same to the nebulizer/humidifier 58. The automaticnebulization can be overridden by a supplemental or manually adjustedcircuit.

Regulated source gas is supplied from the inlet 44 to the regulator 46where it is supplied to the inlet port 51 of the adjustable nebulizercontrol valve 52. Metered gas is supplied at the outlet port 53 from thevalve 52 and is supplied to the nebulizer socket 54. In this way it canbe seen that a nebulizer flow leading the inspiratory flow ofoscillatory gases during automatic operation of the ventilator isprovided. In addition, a common circuit is provided for automatic andmanual continuance of sources of nebulizer/humidifier drive gases.

The reservoir power socket 64 delivers ventilatory and timing gases fromthe scavenger circuit. Scavenged gases are delivered from the outlet 147of the valve 143 from the port 192 of the timing reset cartridge 183 andfrom the outlets of the metering valves 209 and 218 of the oscillatoryvolumetric ventilator module 14. Gases are also scavenged from theoutlet 164 of the failsafe alarm calibration metering valve 163. Theautomatic reservoir refill orifice 179 delivers gas into the scavengecircuit during the volumetric exchange interval. A manually adjustablesource of the reservoir refill gases are delivered from the regulator 46to the inlet port 61 of the reservoir control metering valve 62. Meteredgases are delivered through the output port 63 of the reservoir controlvalve 62 for delivery to the reservoir power socket 64.

From the reservoir refill circuit hereinbefore described it can be seenthat means is provided for automatic refilling of the reservoir duringthe volumetric diffusion interval or inspiratory phase. Timing gases aredelivered during this time through the timing/reservoir refill orifice179 with the rate of delivery being determined by the size of theorifice 179.

Operation of the oscillatory volumetric ventilator module 14 may now bedescribed. Gas is received from the input 44 of the regulator 46 whichis supplied to the input port 48 of the demand CPAP cartridge 49. It isalso delivered through the source isolation check valve 196 and throughthe stabilization reservoir 197 to the inlet 198 of the time cycledmaster switch 199. Gas is delivered from the outlet 201 of the switch199 and is supplied to the inlet port 202 of the normally closedinspiratory time control cartridge 203 and also to the inlet port 204 ofthe normally open expiratory time control cartridge 206. Since theexpiratory time control cartridge 206 is open, gas flows from the inletport 204 through the outlet port 207 and passes through the inspiratoryisolation check valve 208 through the manifold of the metering valve209. Gas then enters the servo port 211 of the normally closedinspiratory time control cartridge 203. As the pressure against thediaphragm of the inspiratory control cartridge 203 increases, thecartridge 203 is moved to the open position and an inspiratory flow ofgas commences with flow through the inlet port 202 to the outlet port213. It will be noted that the gas flow through the cartridge 203 isreverse to that which is conventional, that is, gas from the sourceenters to the rear of the gate valve and applies a constant pressureagainst the diaphragm to provide a sine wave opening of the gate valve.The opening pressures can be adjusted by the springloading provided bythe spring 205. Gas flowing from the outlet 213 of the inspiratory timecontrol cartridge 203 enters the manifold of the flow pressure controlmetering valve 214. Gas then flows through the expiratory isolationcheck valve 216 into the inlet port 217 of the manifold of theexpiratory time control and metering valve 218. Gas from the manifold ofthe expiratory time control metering valve 218 enters the servo port 219of the expiratory time control cartridge 206. When a sufficient pressurerise has been created against the diaphragm, the normally openexpiratory time control cartridge, 206 is moved to a closed position andthe inspiratory time circuit is terminated. With gas flow into theinspiratory circuit cutoff, inspiratory time has started. As gas is bledfrom the inspiratory circuit through the metered outlet from themetering valve 209, within a certain period of time, as determined bythe rate of bleeddown, the inspiratory time control cartridge 203 movesto its normally closed position to terminate the inspiratory interval.Upon termination of the inspiratory interval, pressurization of theinspiratory circuit ceases. The length of the expiratory interval iscontrolled by the bleeding of servoing gas from the metered outlet ofthe metering valve 218. As soon as sufficient bleeddown has occurred,the normally open expiratory control cartridge 206 opens and theexpiratory time is terminated. Gas purged from both the inspiratory andexpiratory timing circuits from the metered outlets of the meteringvalves 209 and 218 is delivered to the entrainment reservoir 69.

From the foregoing, it can be seen that an oscillatory volumetriccircuit 14 with an infinite inspiratory/expiratory ratio has beenprovided. The frequency of oscillation increases with flow through ratesin the metering valves 209 and 218.

The flow pressure metering valve 214 receives inspiratory gas from theinspiratory time control cartridge 203 and delivers a metered flowthrough a low pressure check valve 215 into the inlet port 78 of thefailsafe cartridge 79. Also during inspiration, gas is supplied from theflow pressure metering valve 214 through a fixed metering orifice (notshown) through the servo isolation check valve 135 to the rampingcircuit of the interrupter cartridge 88 by supplying gases to one sideof the check valve 132 and to the servo port 133 of the interruptercartridge 88.

Whenever both the diffusion master switch 92 and the volumetric masterswitch 199 are "on", the volumetric ventilator will command by loadingthe diffusion ventilator timing circuit into an expiratory or volumetricexchange interval. When integrated operation between the diffusion andvolumetric ventilators is functioning, the delay between tidal deliveryfrom the volumetric ventilator and start of oscillatory stroke volumesby the diffusion ventilator is controlled by the interrupter rampingcircuit. The longer it takes servoing gases from the volumetricventilator to bleed out of the oscillator ramping circuit, the longerthe post-inspiratory pause before oscillatory stroke volumes commence.The ramping orifice provides a means for adjusting the post-inspiratorypause.

The volumetric ventilator provides a controlled oscillation atfrequencies to well above 100 cycles per minute. This is mechanicallyaccomplished by a timing circuit which controls a reverse flow normallyclosed spring balanced inspiratory time control cartridge 203.

The oscillatory volumetric ventilator module with CPAP and fail-safealarm includes the demand CPAP cartridge 49. The demand CPAP cartridge49 is provided with a control knob 244 which can be utilized foradjusting the pressure applied to the diaphragm of the cartridge 49through a spring 242. The servo port 109 of the demand CPAP cartridge 49is connected to the airway pressure socket 104 of the patient so thatthe patient on demand can cause opening of the cartridge to permit gasesto flow from the inlet 48 through the outlet 112 and through the CPAPoutput low pressure check valve 113 and through the fail-safe cartridge79 to the main venturi socket 82 and to the nozzle 84 and into theairway of the patient. A further drop in airway pressure accelerates theflow while a pressure rise in airway to the patient retards the flowthrough the CPAP cartridge 49 and as the airway of the patient isfilled, the pressure rises to supply gas under pressure to the servoport 109 to cause the demand CPAP cartridge 49 to retard and close. Thecheck valve 113 prevents backflow from oscillations when CPAP is notemployed. The demand CPAP cartridge 49 provides a means for rapidinspiratory physiological response to minimize the work of breathingwhile maintaining a reliable constant positive pressure withoutexcessive expiratory flow resistance. The pneumatic clutching action ofthe venturi which is controlled by the pressure drop across the venturijet 84 is used to establish a positive end expiratory pressure againstthe physiological airway. The graded expiratory resistance within thethroat of the proximal venturi-like passageway 122 provides a pressurerise above the selection made with the demand CPAP cartridge toterminate demand flow during passive physiological exhalation. Anyoscillatory pressure rise at the proximal airway above the selected CPAPvalue automatically retards flow from the CPAP cartridge 49 andsuperimposes the oscillatory pattern provided by the oscillatorydiffusion module 12.

In order to control oscillation against physiological structures withlow compliance, the CPAP dampening circuit is provided in which gas flowfrom the outlet port 112 delivers gas to the adjustable dampeningorifice 111. Flow from the dampening orifice 111 is delivered to thesensing or servo port of the CPAP cartridge 49. By introducing anaccelerated metered flow of gas from the demand CPAP cartridge 49through the CPAP dampening orifice 111 during dynamic demandinspiration, any constant or lesser flow of gas during the maintenanceof a positive end expiratory pressure creates a snubbing actionlessening tendencies to oscillate against the physiological resistanceof the patient.

The demand CPAP cartridge 49 provides a means for accommodatingspontaneous inspiratory demand. Two distinct oscillatory patterns can beemployed independently or serially upon the basic flow provided by theCPAP demand cartridge 49. Volumetric diffusion respiration can besuperimposed upon the flow provided by the CPAP cartridge 49 allowingspontaneous demand breathing during an extended volumetric exchangeinterval. Additionally, the oscillatory diffusion module 12 canestablish a continuous rapid oscillation with or without CPAP to controlthe partial pressure of oxygen in the arterial blood. This stroke volumecan be periodically topped with a tidal volume delivered by theoscillatory volumetric ventilator to control the partial pressure ofcarbon dioxide in the arterial blood and the pH by provided a masspulmonary exchange. This is accomplished by selecting a constantdiffusion interval on the diffusion module 12 and by programming adesired tidal volume and delivery time on the volumetric module 14. Thisis made possible by servoing of the diffusion module ramping circuitwith the volumetric module during delivery of a tidal volume.

Combination and serialized programming can be obtained by interlockingand sequencing of the three timing circuits, the oscillatory, periodicand volumetric respirator timing circuits hereinbefore described.

The ventilator of the present invention includes a pneumaticalert/fail-safe system to avert trauma should a mechanical or humanfailure occur. The alert/fail-safe servo cartridge 154 is provided witha control knob 173 for adjusting the loading for the cartridge. A sourceof the gas is normally delivered to the inlet port 151 of the mainpressurized calibration metering valve 152 and to one side of the alarmor reset check valve 156. This source gas is metered through the valve152 into the servo port 153 of the failsafe servo cartridge 154. Thesource of gas for the servoing of the fail-safe servo cartridge 154 istaken internally from the main source of ventilatory gases beingdelivered to the venturi nozzle 84. This source of gas is taken from theport 86 which is connected to the port 81 connected to the venturisocket 82. The opening pressure and the alarming time of the fail-safeservo cartridge 154 are dependent upon the pressure of the sourceservoing gas, the spring load against the valve gate and the backpressure in the scavenge circuit. Actuation of the alert/fail-safe servocartridge 154 occurs when there is a sustained pressure rise in the gasbeing delivered to the patient's proximal airway. A transient pressurerise associated with an oscillation is dampened out by the orifice inthe metering valve 152. When a sustained pressure rise occurs, thefail-safe servo cartridge will be moved to an open position and gas willbe supplied through the port 158 to operate the fail-safe indicator 159and the alarm 167.

The demand CPAP servo 49 accelerates the gas flow as essential pressuresfall below programmed values to satisfy physiological inspiratorydemand. The same type of pressure drop will be manifested if a proximalairway disconnect occurs with respect to the patient or if theCPAP/monitoring sensing line becomes disconnected at any point. As theCPAP flow accelerates, pressures in the venturi service circuit areincreased with an associated rise in the source pressures delivered tothe alert/fail-safe servo cartridge 154.

When the source gas pressure rise is sustained above the programmedopening pressure for the fail-safe servo cartridge 154, the fail-safeservo cartridge 154 is opened by servoing gases behind the diaphragm.Gas flow within the fail-safe servo cartridge and to the fail-safecircuit is metered through the metering valve 152, the failsafe servocartridge inlet port 157 and outlet port 158 to the pneumatic fail-safeindicator 159 and also to the servo port 161 of the fail-safe cartridge79 and also to the inlet port of the fail-safe alarm calibration orifice163. From the outlet port 164 of the calibration orifice 163 servoinggas enters the inlet of the alarm isolation and check valve 166 toactivate a pneumatic alarm 167. In addition, servoing gas from theoutlet of the metering valve 163 is directed through the alarm balanceorifice 168 into the scavenging circuit emptying into the entrainmentreservoir 69. Thus it can be seen that the alert/fail-safe system isactivated whenever the pressure of breathing gases flowing to theventuri jet 84 reaches and sustains a pressure above that programmed bythe failsafe servo cartridge 154. The fail-safe cartridge 79 is anormally open reverse flow pneumatic cartridge. Dual inlets 78 and 86provide collateral inlet flow from all ventilatory sources. A "lock up"of the plunger or by the valve poppet is prevented by employing anorifice (not shown) through the poppet stem. Inspiratory gases aredelivered from the outlet 81 of the fail-safe servo to the venturisocket 82.

Should the pressure of respiratory gases be sustained beyond programmedlimits, the fail-safe cartridge 79 will be moved to a closed position atthe same time visible and audible alerts are given by the indicators 159and 167. When the fail-safe cartridge 79 is moved to a closed positionas in the case of a major failure and in turn inducing the high pressurein the respiratory gas circuits, the pressure of gases through thefail-safe servo 79 increases causing the alarm to be sounding withincreasing amplitude.

Whenever pressure is higher at the outlet of the reset check valve 156and inlet port 151, a flow through the adjustable orifice of the meanpressure metering valve 152 occurs causing a pressure rise against theservoing diaphragm and in the antisurge pressure balance reservoir 155.If the pressure rises above the servoing pressure, the fail-safe servocartridge 154 opens and the alert/fail-safe system hereinbeforedescribed becomes dynamic. The mean servoing pressure can be controlledby adjusting the mean pressure rise orifice in the valve 152. Thesmaller the orifice, the more time is required to servo open atpressures above programmed levels.

During oscillatory diffusion or volume delivery in the ventilator, it ispossible for a mechanical failure to occur such as the opening of theflow cartridges well beyond programmed limits. A failure of a flowcartridge would cause a precipitous rise in flow and pressure of gasesin the venturi-like passageway 122. This could produce proximal airwaypressures beyond physiological limits. Should such an event occur, thealert/fail-safe system would alarm and would reduce pressures in theairway below traumatic levels. Therefore, any mechanical failureproducing a runaway flow condition will alarm and be automaticallylocked out. The fail-safe pressure rise produces a unique means ofpressure limiting if limits are exceeded.

Once a lockout has occurred, all programming will remain interrupteduntil the cause of the lockout has been corrected. In most cases,servoing gas locked up within the failsafe servo cartridge 154 will haveto be manually released to reestablish functioning of the ventilator.This is accomplished by dumping the servo circuit through the outletport 172 of the valve 152 by operation of the normally closed manuallyactuated reset push button 171 to ambient. Should the cause of thelockout not be corrected before reset, an immediate lockout will berepeated.

The alert/lockout system used in the present ventilator utilizes sourcegas pressures for causing servoing of the failsafe servo cartridge 154rather than using traditional breathing circuit pressures. In addition,the alert/lockout system utilizes mean pressures rather than relying ona pressure rise or a time constant.

The universal breathing circuit 16 includes an encapsulated venturi ashereinbefore described which provides a means of rapid pressure rise anddrop at the physiological airway during rapid oscillation. Duringexhalation from the patient's airway, gases flow around the distal endof the venturi assembly and reach ambient through the exhalation valve228. The exhalation valve 228 is normally open and is kept in phase withthe stroke volume delivery by the adjustable phasing orifice 231connected to the servo port 229.

The use of the normally open exhalation valve reduces the work ofbreathing in case of total failure of gas delivery by acting as afail-safe device for satisfying physiological demand. The exhalationvalve cannot mechanically lock up the physiological airway because itparallels the venturi passageway which is in communication with theexpiratory gate 227.

The universal breathing circuit 16 in the present invention has numerousadvantages. It prevents rebreathing of exhaled gases. It permitsmonitoring of the proximal airway pressure. It eliminates the potentialfor the lockup of an exhalation valve.

In FIG. 2 there are shown the curves resulting from a theoreticalstabilized patient on intermittent percussive ventilation (I.P.V.) withdemand constant positive airway pressure (CPAP). The curves inparticular show the oscillatory ramping up of pressure during thediffusion interval (inspiratory phase) and the percussive clutchingwhich occurs in the venturi-like passageway as the patient's airway isfilled. The functional residual capacity (F.R.C.) increases anddecreases as indicated during the inspiratory and expiratory phases. ACPAP of 5 cm H₂ O is shown.

In FIG. 3 there is shown another embodiment of the invention which issubstantially simpler in construction than the embodiment of theinvention shown in FIG. 1. It consists of a power control module 261, atransport service module 262, an alarm control module 263, a volumetricdiffusion respirator module 264 and a breathing circuit 266. The powercontrol module 261 is substantially identical to the power controlmodule 11 disclosed in the previous embodiment and therefore it will notbe described in detail. As can be seen, the various components of thepower control module are identical to the components disclosed in theprevious embodiment. In addition, the mode of operation is the same.

The transport service module 262 consists of two regulators 271 and 272in which regulator 271 can be characterized as an oscillator pressureregulator and the regulator 272 can be characterized as a time cycleregulator. Gas is supplied from the outlet 24 of the oxygen blender 21of the power control module to an aspirator power socket 273 of thetransport service module 262. In addition, unregulated gas is suppliedthrough the inlet 274 of the master on/off switch 276. The master on/offswitch 276 is provided with a control knob 277 so that the master on/offswitch can be switched manually "on" or "off" by use of the knob 277.When the master on/off switch 276 is turned on, regulated gas issupplied from the inlet 274 to the outlets 278 and 279. Gas is suppliedfrom outlet 278 to the inlets 281 and 282 of the regulators 271 and 272.When the switch 276 is in the off position gas is supplied from theinlet 274 through an outlet 279 and through a check valve assembly 280for a purpose hereinafter described.

The oscillator pressure regulator can be set for a predeterminedpressure and from a range of 0 to 100 psi; for example, 50 psi foradults and 25 psi for babies. Regulated gas is supplied at the desiredpressure from the oscillator pressure regulator 271 through its outlet283. Gas from the outlet 283 is supplied through an adjustable gaugeorifice 284 to a gauge 286 which supplies a visual reading of theoscillator operating pressure. Regulated gas is also supplied to theinlet 287 of a pneumatically-controlled flow oscillator cartridge 288.The flow oscillator cartridge 288 forms a part of the alarm/controlmodule 264. The flow oscillator cartridge 288 is provided with an outlet289 which is connected through an oscillator inspiratory isolation checkvalve assembly 291 to the inlet 292 of an oscillator inspiratory time onneedle valve 293 which is carried by the flow oscillator cartridge 288.The adjustable needle valve 293 is provided with an outlet 294. Gaswhich is metered through the needle valve 293 is supplied to a servoport 296. Gas supplied to the servo port 296 servoes the flow oscillatorcartridge into the closed position to interrupt the flow of gas from theinlet port 287 to the outlet port 289. This interrupts the flow ofservoing gas to the servo port 296. Gas behind the diaphragm of the flowoscillator will then flow out of the servo port 296 to the inlet 297 tothe oscillator expiratory time off needle valve 298 and then through itsoutlet 299. The outlet 299 is connected to an inlet 301 of an oscillatortiming reset cartridge 302. The oscillator timing reset cartridge 302carries the oscillator expiratory time off needle valve 298. The inlet301 in the oscillator timing reset cartridge is in the open position andis in communication with an outlet 303 which is connected to an inlet304 of an interval phasing cartridge 306. The inlet 304, when theinterval phasing cartridge is in the open position, is in communicationwith an outlet 307. The outlet 307 is connected through a frequency bandadjustment needle valve 308 which is connected to a servo port 309 ofthe oscillator timing and reset cartridge 302. At the same time that thegas is delivered to the frequency band adjustable needle valve 308, gasis also supplied to a service socket 311. A fitting 312 is mounted inthe service socket 311 and is connected to an entrainment gate 313. Thesocket 313 is connected into an entrainment reservoir 314. Regulated gasin addition to flowing through the oscillator inspiratory isolationcheck valve 291 flows to the right to an inlet 316 of an oscillatoryamplitude needle valve 317 which is carried by the interval phasingcartridge 306. The metered gas is supplied to the outlet 318 of theoscillatory amplitude needle valve assembly 317 which is connected to anservice socket 319. An inlet fitting 321 is mounted in the servicesocket 319 and is connected to the venturi jet 322 of a venturi assembly323. Thus it can be seen that by adjustment of the oscillatory amplitudeneedle valve assembly 317 it is possible to adjust the amplitude of theoscillations in the metered gas. Even though as is being supplied to theventuri jet 322, sufficient back pressure is developed so that gas isalso supplied through the oscillator inspiratory isolation check valveassembly 291 for metering the gas. This metered gas is supplied throughthe isolation inspiratory time off needle valve assembly 298 but the gascan go no further because the oscillator timing reset cartridge is nowin a closed position because of the gas previously supplied to the servoport 309 to servo it into the closed position. Since this is the case,gas pressure will build up in the servo port 296 until sufficientpressure has been built up behind the diaphragm to move the flowoscillator cartridge 288 to a closed position. As soon as this occurs,flow of gas is interrupted through the flow oscillator cartridge 288. Assoon as this occurs, the gas which is behind the diaphragm in theoscillator timing reset cartridge 302 is bled down to permit it to moveto its normally open position. This bleed down occurs through theoscillatory amplitude needle valve assembly 317 and through the venturijet 322. It also occurs through the frequency band adjustment needlevalve assembly 308 and dumps into the reservoir 314. There is then acontrolled flow of the gas from behind the diaphragm in the flowoscillator cartridge 288. This flow passes from the servo port 296through the oscillator expiratory time off needle valve assembly 298through inlet 301 and the outlet 303 of the oscillator timing resetcartridge 302, since it is now in its normally open position, andthrough the normally open interval phasing cartridge 306 and into theentrainment reservoir 314. As soon as there has been sufficient dumpingof gas from behind the diaphragm of the flow oscillator cartridge 288,the flow oscillator cartridge 288 moves to its normally open positionand the gas begins to flow into the servoing port 309 of the oscillatortiming reset cartridge 302 to move it to a closed position to completethe sequence.

As hereinbefore pointed out, gas is supplied to the time cycle regulator272 of the transport service module 262 at the time that the masteron/off switch 276 is turned on. The outlet 326 of the regulator 272 isconnected to the inlet 327 of a flow cartridge 328 which forms a part ofthe volumetric diffusion respiration module 264. The flow cartridge 328is in a normally open position and therefore gas supplied to an inlet327 normally flows through an outlet 329 and then through a servoingisolation check valve 331 to the servo port 332 of the interval phasingcartridge 306 to servo it into the closed position. The interval phasingcartridge 306 can provide a variable delay. For example, a delay fromone to six seconds can be provided as determined by the position of theadjustable oscillatory delay needle valve assembly 333 which is incommunication with the entrainment reservoir 314.

At the time that gas is supplied to the flow cartridge 328, when in itsnormally open position, gas is also supplied to a servo port 334 of thetiming reset cartridge 336 to move it to a closed position from itsnormally open position. At the same time, gas is also supplied from theoutlet 329 through an inspiratory isolation check valve 337 to the inlet338 of an inspiratory time needle valve assembly 339. The outlet 341 ofthe needle valve assembly 339 is connected to the servo port 342 of theflow cartridge 328 to servo it to a closed position after sufficient gashas flowed through the needle valve assembly 339.

As soon as gas is no longer supplied to the servo port 309, the gas isbled down through the servo isolation check valve 331 through theoscillatory delay needle valve assembly 333 to the entrainment reservoir314. This permits the timing reset cartridge to move to its normallyopen position. Also as soon as flow is interrupted through the flowcartridge 328, gas behind the servoing diaphragm of the cartridge 328 isbled out of the servo port 342 through the inlet 343 of an expiratorytime needle valve assembly 344 which is carried by the timing resetcartridge 336. Gas flows through the outlet 346 of the needle valveassembly 344 to the inlet 347 of the timing reset cartridge 336 which isnow in its open position and gas flows through the outlet 348 which isconnected into the entrainment reservoir 314. As soon as sufficientbleed down of gases from behind the diaphragm of the flow cartridge 328has occurred the flow cartridge 328 will move to its normally openposition to again permit gas from the time cycle regulator 272 to flowout of the outlet port 329 to start the cycle anew.

In order to prevent the timing reset cartridge 336 from locking up andalso to provide range compensation, an orifice 351 is provided which isconnected to the servo port 334 and is also connected to the entrainmentreservoir 314. This orifice 351 can be of a suitable size such as 0.013inch. Gas from the servo port 334 also can flow through a flow pressureneedle valve assembly 352 and then through a ventilator output lowpressure check valve assembly 353 into the venturi jet 322.

Means is provided for providing manually controlled inspiration andincludes a manually operated inspiration valve 356 having a manuallyoperable push button 357. Regulated gas is supplied from the outlet 326of the time cycled regulator 272 and is supplied to the inlet 358 of themanual inspiration valve 356. The outlet 359 of the manual inspirationvalve 356 is connected into the pneumatic circuitry so that gas suppliedthrough the manual inspiration valve 356 is supplied through the flowpressure needle valve assembly 352 and to the ventilator output lowpressure check valve assembly 353 directly into the venturi jet 322.

A demand CPAP (constant positive airway pressure) cartridge 361 isprovided as part of the alarm/control module 263. The cartridge 361 isprovided with a control knob 362 which is provided for adjusting thepressure that is supplied to the diaphragm as hereinbefore described inconjunction with the demand CPAP cartridge 49 in the previousembodiment.

The demand CPAP cartridge 361 is provided with regulated gas from thetime cycle regulator 272 which is supplied to the input 363 of thecartridge 361. When the cartridge 361 is in an open position, gas issupplied through an outlet 364 through a low pressure check valveassembly 366 and to the venturi jet 322. Means is provided forconnecting the demand CPAP cartridge to the patient airway, and consistsof a sensing port 367 which is connected to an outlet 368. An inlet 369is connected to the outlet 368 and is in communication with the patientairway through an inlet 371 provided in the venturi assembly 323. Thusis can be seen that in the event the patient requires breathing gases tobe supplied the patient will cause reduced pressure to be providedbehind the diaphragm of the CPAP cartridge 361 to cause it to move to anopen position and to permit breathing gases to be supplied directly tothe venturi jet 322. Means is provided for dampening movement of thediaphragm of the demand CPAP cartridge 361 and consists of a dampeningorifice 372 which is connected between the outlet 364 and the sensingport 367. This prevents undesirable oscillation in the demand CPAPcartridge.

The alarm/control module 263 also includes a fail-safe servo cartridge376 which is provided with a control knob 377 for adjusting the pressureunder which the fail-safe servo will move from its normally closedposition to an open position. Gas is supplied from the venturi socket319 to the inlet 378 by means of a pressure calibration needle valveassembly 379 having an outlet which is connected to the servo port 381of the fail-safe servo cartridge 376. At the same time, gas is suppliedfrom an outlet 382 of the needle valve assembly 379 and is incommunication with an anti-surge pressure balance reservoir 383 throughan alarm reset check valve assembly 384 to the inlet 378. The reservoir383 is also connected to an alarm reset check valve assembly 384 whichis connected to the fitting 319 connected to the venturi jet 322. Theventuri jet 322 is also connected to the inlet 378 of the fail-safeservo cartridge 376. The cartridge 376 is provided with an outlet 386which is connected to the inlet 387 of a fail-safe cartridge 388. Theoutlet 386 is also connected to a fail-safe bleed orifice 389 of asuitable size such as 0.013 inches which is connected to the entrainmentreservoir 314.

When gas is supplied through the inlet 387 of the fail-safe cartridge388, the fail-safe cartridge is servoed from its normally closedposition to an open position. As soon as this occurs, gas is suppliedfrom the venturi jet 322 through an inlet 391 through an outlet 392. Gaspassing through the outlet 392 passes through an alarm orifice 393 of asuitable size such as 0.024 inches which gives an audible alarm. Inaddition, gas is supplied to an alarm pressure relief governor 396 whichdumps gas to the atmosphere and will also give an audible alarm. Alsopressure is supplied to a fail-safe indicator 397 to indicate that thefail-safe circuitry has been called into action. In this way it can beseen that the gas which would normally be delivered to the patient isreleased into the atmosphere to drop the pressure substantially while atthe same time giving alarms without locking out the ventilator. Manuallyoperated reset means for resetting the fail-safe servo cartridge 76 isprovided and consists of a manually operated switch 398 having its input399 connected to an output 400 of the needle valve assembly 379.

The breathing circuit 266 is substantially identical to the breathingcircuit 16 disclosed in the embodiment shown in FIG. 1 and for thatreason will not be described in detail. The alarm/control module 263 hasmeans for supplying gas to the nebulizer 58 of the breathing circuit 266which includes a nebulizer control needle valve assembly 401 which hasits inlet 402 connected to the outlet 24 of the blender 21 and has itsoutlet 403 connected to an outlet socket 404. An inlet 406 is connectedto the outlet 406 which is connected to the nebulizer 58.

Means is provided for presenting a numerical readout to the clinicianand consists of a cartridge 413 which has an inlet 414 connected to anoutlet 415 of the oscillatory amplitude needle valve 317. The cartridge413 carries a paddle 416 carried by a spring loaded shaft 417. The shaftis driven by a diaphragm 418. Thus it can be seen that when thediaphragm 418 is loaded when gas is supplied through the inlet port 414,the paddle 416 is moved outwardly against the force of a spring 419carried by the shaft 417. As soon as the pressure behind the diaphragm418 is relieved, the paddle 416 will be returned under the force of thespring 419.

The paddle 416 is used for breaking a beam from a source of energy toinitiate a signal which can be utilized to provide a numericalpresentation for each movement of the paddle. By way of example, asource of infrared energy can be positioned on one side of the paddleand means for sensing infrared energy can be positioned on the otherside of the paddle. The paddle 416 is positioned in such a manner sothat with each pressurization of the cartridge 413 the paddle 416 willonly interrupt the beam of energy at the end of travel to prevent adouble interruption during each oscillatory cycle of the ventilator.

Operation of the embodiment of the invention shown in FIG. 3 may now bebriefly described as follows. Let it be assumed that it is desired toventilate a patient and that the breathing circuit 266 has beenconnected to the patient. The blender 21 is adjusted to supply anappropriate mixture of gases such as a mixture of 60 percent oxygen and40 percent air. Let it be assumed that the master on/off switch 76 hasbeen turned on to supply gas to both of the regulators 271 and 272. Withthe master on/off switch 276 in an off position, source gas is directedthrough the manual on/off switch 276 through the inlet port 274 andthrough the outlet port 279 into the auto load isolation check valve 280to deliver gas into the servo port 342 of the cartridge 328 and into theservo port 334 of the cartridge 336 to hold the ventilator in anexpiratory phase. With the expiratory time metering valve 344 in thefull clockwise off position leakage from the timing circuit is zero. Nowlet it be assumed that the master on/off switch 276 has been turned tothe "on" position to supply gas to both of the regulators 271 and 272.Gas is supplied from the regulator 271 to the flow oscillator cartridge288. Gas flow through the flow oscillator cartridge 288 initiatesclosing of the oscillator timing reset cartridge 302. Gas from the flowoscillator cartridge 288 also is supplied to the oscillatory amplitudeneedle valve assembly 317 which is utilized to control the pressure atthe physiological airway of the patient and supplies the gas to theventuri jet 322 and also to the exhalation valve assembly 228 to closethe same. This commences the pulsation of gas which will hereinafter bedescribed. The duration of the pulse of gas is determined by the lengthof time required to servo the flow oscillator cartridge 288 closed. Gasflows through the oscillator inspiratory isolation check valve assembly291 through the oscillator inspiratory time on needle valve assembly 293to the servo port 296 of the flow oscillator cartridge 288.Concommitantly, gas is supplied to the oscillator inspiratory time offneedle valve assembly 298 where it comes into contact with the nowclosed oscillator timing reset cartridge 302. Gas thus builds up underpressure in the flow oscillator cartridge 288 to servo the same to aclosed position within a period of time determined by the adjustment ofthe needle valve assembly 293. As soon as the flow oscillator cartridge288 is moved to a closed position, the flow of gas to the venturi 322and to the exhalation valve assembly 228 is interrupted, permitting theexhalation valve assembly 228 to open to permit the pressure in thephysiological airway to drop towards atmospheric pressure.

The length of time which is taken for dropping to or above atmosphericpressure is determined by the adjustment of the oscillator inspiratorytime off needle valve assembly 298. The routing of bleed off gases isfrom behind the diaphragm of the flow oscillator cartridge 288 throughthis oscillator expiratory time off needle valve assembly 298 to theoscillator timing reset cartridge 302 which is now in an open positionthrough the interval phasing cartridge 306 to the entrainment reservoir314. As soon as the pressure has been reduced sufficiently, the flowoscillator cartridge 288 will move to its normally open position whichthen permits the gas to flow to the patient. The oscillator timing resetcartridge 302 is again moved to a closed position and the cycle isrepeated.

Thus as shown in FIG. 4, there is provided a plurality of generallytriangular shaped oscillations 416. The time interval which is utilizedfor the diffusive portion of the ventilatory cycle is determined by thetiming provided by the flow cartridge 328 provided in combination withthe timing reset cartridge 336. Gas is delivered through the flowcartridge 328 and then through the flow pressure needle valve assembly352 through the ventilator output low pressure check valve assembly 353to the venturi jet 322. At the same time, gas is also supplied throughthe servoing isolation check valve 331 to the servo port 332 of theinterval phasing cartridge 306 to move it to a closed position. As soonas this occurs, the source of oscillatory pulses to the patient's airwayis interrupted. As gas is supplied to the flow cartridge 328, gas isalso supplied through the inspiratory isolation check valve assembly 337to the inspiratory time needle valve assembly 339 to supply gas to theservo port 342. Gas at the same time is supplied to the inspiratory timeneedle valve assembly 344 and to the timing reset cartridge 336 which isin a closed position.

Therefore, gas builds up in the flow cartridge 328 to servo it to aclosed position after a predetermined length of time determined by thepositioning of the inspiratory time needle valve assembly 339. Because alonger period of time is desired, the inspiratory needle time needlevalve assembly is provided with a finer adjustment and with acorresponding oscillator inspiratory time on needle valve assembly 293.As soon as the flow cartridge 328 has been moved to a closed position,the flow of gases in the interval phasing cartridge 306 is interruptedand the gas behind the servo diaphragm is bled down through theoscillatory delay needle valve assembly 333 to the entrainment reservoir314. The delay provided by the needle valve assembly 333 determines thepost volumetric delivery pause. The period of time which is taken fordelivering the tidal volume to the patient is shown by the curve 417 inFIG. 4. As soon as the flow of gases is interrupted by the flowcartridge 328, the exhalation valve assembly 228 is allowed to openpermitting the patient to exhale. The length of time during which thepatient exhales is determined by the adjustment of the expiratory timeneedle valve assembly 344.

As soon as the flow of gases through the flow cartridge 328 isinterrupted, the gas which is holding the timing reset cartridge 336closed is bled out and passes through the flow pressure needle valveassembly 352 through the ventilator output low pressure check valveassembly 353 and into the venturi jet 322. Bleed down continues untilthe timing reset cartridge 336 moves to its normally open position whichis represented by the curve 423 in FIG. 4. At the same time, gas is alsobled out from behind the diaphragm in the flow cartridge 328 through theexpiratory time needle valve assembly 344 through the timing resetcartridge 336 to the entrainment reservoir 314.

In the event that the flow pressure needle valve assembly 352 is in afully closed position, oscillation will still be brought about becausethe gases under pressure behind the diaphragm of the timing resetcartridge 336 can bleed down through the range compensator orifice 351into the entrainment reservoir 314. This ensures that the volumetrictiming circuit cannot be locked up accidentally.

In the embodiment of the invention shown in FIG. 3, even when manualinspiration is provided by use of the manual inspiration valve 356, thegas under pressure supplied to the patient is controlled by the flowpressure needle valve assembly 352.

As soon as the flow cartridge 328 moves to an open position, the cyclehereinbefore described will be repeated in which the diffusiveoscillation will first take place followed by the volumetric exchange.As shown in FIG. 4 it is possible to provide a pause after thevolumetric exchange which can be utilized to introduce CPAP if desired.CPAP can be provided by turning the CPAP control knob 362 to the "on"position and to provide a desired level of CPAP by adjusting thepressure on the diaphragm. The CPAP cartridge provides a floor or baseline against which the patient must exhale. If desired, a pause can beprovided without CPAP followed by diffusive oscillation.

It should be appreciated that if desired, the interval phasing cartridge306 can be omitted, in which event, the oscillatory pattern provided bythe flow oscillator cartridge and the oscillator timing reset cartridge288 and 302 respectively, would provide an oscillatory patternsuperimposed on the volumetric exchange pattern provided in FIG. 4.

In utilization of the embodiment of the invention shown in FIG. 3 it isalso possible to provide oscillatory demand CPAP. This can beaccomplished by establishing the desired constant positive airwaypressure by appropriate adjustment of the knob 362 ranging typicallyfrom five to ten centimeters of water and thereafter closing theexpiratory time valve assembly 344. This will establish a diffusiveoscillatory pattern on top of the CPAP. The frequency of pulsation iscontrollable by adjustment of the oscillator inspiratory time on needlevalve assembly 293 and adjustment of the oscillator expiratory time offneedle valve assembly 298 with the amplitude of the pulses beingcontrolled by the adjustment of the oscillatory amplitude needle valveassembly 317. The advantage of such a procedure is that is effectivelycloses the right to left pulmonary shunt providing an oscillatory bloodgas interface on top of the CPAP.

The frequency band adjustment needle valve assembly 308 is utilized foradjusting the frequency band. This is accomplished by controlling therate of bleeding from the expiratory circuit for the flow oscillator andoscillator timing reset cartridges 288 and 302. By increasing the rateof bleedoff, a higher frequency can be obtained. Conversely, bydecreasing the rate of bleedoff of gases from the expiratory circuit, alower frequency can be obtained.

It should be appreciated that each time a pulse is produced by theventilator shown in FIG. 3 the fail-safe circuitry is reset. This isaccomplished because each time gas is accumulated in the reservoir 383it is bled off through the alarm reset check valve 384 into thebreathing circuit 266. It is only when there is an accumulated meanpressure which is greater than that determined by the adjustment of theknob 377 on the fail-safe servo cartridge 376 that an alarm isinitiated. The fail-safe servo cartridge 376 activates the fail-safecartridge 388. As soon as the fail-safe cartridge 388 opens, gas is bleddirectly from the venturi jet 322 through the alarm pressure reliefgovernor 396 to the atmosphere. At the same time, the fail-safeindicator alarm 397 is actuated, as hereinbefore explained, a parallelalarm is also actuated by activation of the alarm 394 through the alarmorifice 393. The alarm orifice 393 prevents overwhelming of the reeds inthe audible alarm 394. The governor 396 provides a backup alarm to thesound which is created by the alarm 394 during the time that the gas isbeing released into the atmosphere. The amount of noise created by thegovernor 396 is determined by the rate of flow of gas through the same.

The manner in which the timing circuit for the ventilator in FIG. 3 isloaded by the use of the master on/off switch and the check valve 280prevents a potentially large initial tidal volume delivery to thepatient when the master on/off switch 276 is turned to the "on" positionand when the inspiratory time selection is near maximum. The circuitutilized in the present invention virtually eliminates any possibilityof malfunction of the automatic phasing as, for example, could occur onand off through the master on/off switch 276 without sufficient time forthe auto load system to reset.

An improved breathing circuit 429 is shown in FIG. 5 which can beutilized with the embodiments of the invention shown in FIGS. 1 and 3.As shown in FIG. 5, the breathing circuit includes a breathing headassembly 431 which has mounted thereon a nebulizer assembly 432. Thebreathing head assembly 431 consists of a patient adapter 433 which canbe of any suitable type such as a mouthpiece, a mask, or endotrachealtube, which is connected to the lungs of the patient which arerepresented by the balloon 434. The breathing head assembly 431 alsoconsists of a shrouded venturi assembly 436. A venturi manifold assembly437 also forms a part of the breathing head assembly 431 and is mountedupon the shrouded venturi assembly 436. An exhalation valve assembly 438is also mounted upon the shrouded venturi assembly 436.

The shrouded venturi assembly 436 consists of an outer cylindricalmember 441 and an inner cylindrical member 442 as well as cylindricalextensions 443 and 444 extending diametrically of the member 441.Suitable means is provided for supporting the inner cylindrical member442 within the outer cylindrical member 441 while at the same timeretaining freedom of flow of gases between the cylindrical members 441and 442 and through the cylindrical extensions 443 and 44. Thus therecan be provided an annular flange 446 formed integral with one of thecylindrical members 441 and 442 as for example on the inner cylindricalmember 442 which frictionally engages the other cylindrical member. Theinner cylindrical member 442 is provided with a venturi-like passageway447.

The venturi manifold assembly 437 consists of a cylindrical member 448which is carried by the inner cylindrical member 442. It carries aventuri jet 449 which is positioned in such a manner so that a jet ofgas passing therefrom is axially aligned with the venturi-likepassageway 447 provided in the inner cylindrical member 442. Gas issupplied to the venturi jet through a line 451 which is connected to afitting 452. The line 451 is also connected to the inlet 453 of theexhalation valve assembly 431 so that during the time that gas is beingsupplied to the venturi jet 449, gas is supplied to a diaphragm 454 ofthe exhalation valve assembly 438 to hold the exhalation valve 456 in aclosed position.

The venturi manifold assembly 437 has diametrically opposed cylindricalextensions 458 and 459 formed thereon. The cylindrical extension 458 hasan expiratory gate valve 461 mounted therein through which gases canescape to the atmosphere. The cylindrical extension 459 is connected bya large tube 462 to an inlet fitting 463 formed on the cap 464 of anebulizer 466. The cap is provided with another fitting 467 which isconnected by a large tube 468 to the exhalation valve assembly 431. Atube 468 is also connected to an inlet 469 which has an entrainmentreservoir 471 mounted thereon. The inlet 469 is provided with an ambiententrainment gate 472 to permit entrainment of ambient air when required.The entrainment reservoir 471 is provided with a flexible overfill gate473.

The shrouded venturi assembly 436 is provided with a fitting 476 whichis connected by a line 477 to an inlet fitting 478 to make it possibleto monitor the patient airway pressure. The fitting 469 is provided withan adapter 479 which is connected by a line 481 to a fitting 482 so thatauxiliary gas can be bled into the reservoir 471. The nebulizer cap 464is provided with an inlet fitting 483 which is connected by a line 484to a fitting 486 to permit gas to be supplied to operate the nebulizer466 in a manner well known to those skilled in the art.

The nebulizer assembly 432 consists of a generally cylindrical body 491which is mounted by a slip fit onto the cylindrical extension 444provided on the shrouded venturi assembly 436. A bottom reservoir cup492 is adapted to be mounted by a slip fit onto the bottom end of thebody 491 and is adapted to contain a suitable medication such as tenmillimeters of a solution that could be utilized in connection with thenebulizer. The body 491 is provided with means for preventing themedication solution from spilling from the nebulizer once the reservoircup 492 has been placed on the body. This consists of a baffle 493 whichis formed of a hollow cylindrical member 494 disposed concentricallywithin the body 491 and having a diameter substantially less than theinner diameter of the body 491. The cylindrical member 494 is carried bya circular disc-shaped member 496 formed integral with the body 491 andintegral with the upper extremity of the cylindrical member 494. Amember 497 is mounted in the cylindrical body 491 and above thedisc-shaped member 496. It is provided with a venturi-like flow passage498 and is also provided with a nozzle or jet 499 in axial alignmentwith the passage 498. The jet 499 is connected to a line 501 which isadapted to be connected to the nebulizer fitting 486. The jet or nozzle499 is disposed in such a manner so that gases jetting therefrom willpass through the venturi-like flow passage and will impinge upon a ball502 mounted on the interior surface of the body 491. The venturi-likeflow passage is also in communication with a capillary tube 503 whichextends downwardly through the hollow cylindrical member 494 asufficient distance so that it extends into the liquid 504 providedwithin the reservoir cup 492.

Means is provided for manually cycling the nebulizer 432 and consists ofa cylindrical member 506 which is mounted exterior of the body 491. Avalve member 507 is mounted within the cylindrical member and is adaptedto be moved into and out of engagement with a valve seat 508. Operatingbutton 509 is provided for moving the valve member 507 to an openposition against the force of a spring 511. Gas from a suitable sourceof pressure is supplied to a line 512 connected to the cylindricalmember 506. The interior of the cylindrical member 506 is connected by apassage 513 into the interior of the body 491.

Operation of the breathing circuit 429 shown in FIG. 5 can now bebriefly described as follows. Let it be assumed that it is desired touse the same in an intensive care situation in which the shroudedventuri assembly would be connected by an endotracheal tube to thepatient. Let it be assumed that the exhalation valve 456 has justopened. When this occurs, the exhaled gas passes through the large tube458 into the entrainment reservoir and into the nebulizer 456 and thento the tube 462 and into the venturi manifold assembly 437. The exhaledgas is released to the atmosphere through the gate valve 461 provided inthe venturi manifold assembly. In addition, surplus gas is alsodischarged to the atmosphere through the overfill gate 473 provided as apart of the entrainment reservoir 471. It should be pointed out thatnormally there is a slight delay in the opening of the exhalation valveand that prior to this time, the venturi jet will be depressurized andthe initial exhalation gases will pass through the expiratory gate valve461. Within a short period of time thereafter, the exhalation valve 456opens to provide a parallel path for the excape of exhalation gases fromthe airway of the patient. The exhalation circuitry cannot becomepressurized because the flap 473 on the bottom of the entrainmentreservoir opens as hereinbefore explained.

The amount of rebreathing of gases can be readily controlled by the flowof additional gases through the nebulizer and into the reservoir. Thesefresh gases entering the breathing circuit serve to reduce the CO₂content of the rebreathed gases thereby making it possible to preciselycontrol the CO₂ content of the rebreathed gases and to keep the same toan acceptable level so as to prevent hyperventilation. The largenebulizer 466 can be utilized to provide the desired humidification forthe gases supplied to the patient. The small nebulizer 432 can beutilized for supplying certain desired drugs to the humidified gasesbeing supplied to the patient. The drugs are introduced in liquid forminto the reservoir cup 492. When gas is supplied to the jet 492, it willpass through the venturi-like passage 498 to cause the liquid drug 504to be brought up from the reservoir cup 492 to the venturi passage andwill cause the drug droplets to impinge upon the ball 502 and cause thesame to be broken up into a fine mist. This fine mist of particles iscarried upwardly into the shrouded venturi assembly 436 by gases whichare introduced into the body 491 by operating the pushbutton 509 to movethe valve member 507 to an open position to permit gases to be suppliedfrom the line 512 into the cylindrical area provided between the outercylindrical member 441 and the inner cylindrical member 442 and to causethe same to be moved into the airway of the patient. Many largeparticles carried into the shrouded venturi assembly may impinge uponthe inner cylindrical member 442 and eventually fall off and rain intothe body 491 of the venturi assembly 432. The droplets will collect ontothe disc-shaped member 496 and will pass downwardly into the cupreservoir in the cylindrical space provided between the inner surface ofthe cylindrical member 494 and the outer surface of the capillary tube503.

In addition to the use of the nebulizer 432 shown in FIG. 5, typically,the patient adapter would be in the form of a mouthpiece. Also in suchan arrangement, the tube 468 could be omitted so that the exhalationvalve will empty directly to the atmosphere. In addition, the tube 462can be removed and the cylindrical extension 459 can be plugged. Thenebulizer 432 is designed as a hand-held unit and in such a manner sothat the drug contained in the reservoir cup is non-spillable. It isnon-spillable because in the event the hand-held unit is tipped on itsside, there is sufficient volume within the interior of the body 491 toaccommodate the liquid drug 504 within the reservoir cup 492 so that itwill not rise to a level at which the liquid could pass through theinterior of the cylindrical member 494. The disc-shaped member 496prevents the escape of the liquid from the reservoir cup 492. Thus thenebulizer 432 can be readily used as a hand-held unit without any dangerof spilling the drug contained therein.

During the time that gases are being delivered from the shroudedcircumferential area into the airway of the patient, gases are alsobeing supplied through the venturi passage 447 driven by the gases fromthe jet 449 also into the airway of the patient in a direction parallelto the path of the flow of gases through the circumferential shroudedarea of the venturi assembly to thereby create an effective mixing ofthe gases delivered to the airway of the patient.

In summary, it can be seen that the jet 499 in combination with thecapillary 503 produces a spray of large particles which extends acrossthe body 491 where they impinge upon the hemisphere or ball 502 to forma fractured aerosol. This fractured aerosol is delivered into thecircular plenum area of the encapsulated or shrouded venturi assembly436 to cause a whirling mixing action to occur. The aerosol is thensupplied to the patient airway and at the same time is mixed with gasesdelivered through the venturi-like passageway 447. In this wayconcentric flows of gases are delivered to the airway of the patient.

When the breathing circuit shown in FIG. 5 is used in conjunction withthe embodiment of the invention shown in FIG. 3 pulsatile stroke volumesare precisely delivered onto the hemisphere to provide a pulsatilevolume of vehicular gas for the transport of an aerosol upward into theshrouded area. The rate of oscillatory stroke volume increases withhigher oscillatory frequencies and the rate of aerosol transport isconcommitantly upgraded. A pulse of discharged gas from the oscillatortiming circuit occurs prior to the actual stroke volume delivery causinga bolus of aerosol to reach the distal venturi at almost the precisetime the oscillatory volume of therapeutic gas is injected. The dualpathways provided for the gases supplied to the airway of the patientplay a major role in maximizing oscillatory stroke volume and minimizingmechanical dead space. At the moment of expiratory phasing betweenoscillations or a pause, gas flow through the venturi reverses toambient through the flapper valve 461 which is followed by opening ofthe exhalation valve 456. This provides for a larger proximal airwaypressure differential during successive oscillations, thereby makingpossible a larger stroke volume delivery into the pulmonary structuresenhancing mechanical mixing of the gases.

In the breathing circuit shown in FIG. 5, a controlled partialrebreathing circuit is provided by the use of the large tube 468 whichconnects the exhalation valve assembly 431 to the manifold 469 connectedto the distensible bag 471. The distensible bag, or reservoir 471 whichis provided with the overfill gate 473 provides a low pressure ambientvalve and accommodates ambient venting when large physiological volumesare rapidly expelled into the breathing circuit. During inspiration, gasmay be entrained from the distensible reservoir 471 or from ambientthrough the ambient inlet valve 472 should the gas supply in thereservoir 471 be depleted. Expiratory stroke volumes are deliveredpreferentially through the exhalation valve port 443 through the largetube 468 into the distensible reservoir 471 to ambient through the cap464 of the large nebulizer 466 and through the tube 462 through theexhalation gate 461 provided on the venturi manifold assembly 437.

With the breathing circuit 429 shown in FIG. 5 pulsatile pressures canbe regulated to provide substantially constant values within thebreathing circuit while at the same time accommodating many ventilatorytechniques. Carbon dioxide concentrations in the circuit can bemaintained at optimal levels minimizing the hyperventilatory tendencies.By controlling the washout (decrease) of carbon dioxide by controllingthe amount of new gases supplied into the breathing circuit, the carbondioxide level can be precisely controlled and metered gases can bedelivered on a constant flow basis into the breathing circuit.

In FIG. 6 there is disclosed an embodiment of a ventilator incorporatingthe present invention which can be characterized as an intermittentpercussive ventilator. A source of gas is provided of a conventionaltype such as an appropriate mixture of air and oxygen from a blender 21of the type hereinbefore described in the previous embodiments. Thisair/oxygen source is supplied through a filter 521 to the inlet 522 of arotary pneumatic on/off switch 523. The rotary on/off switch 523 isprovided with a control knob 524 for operating the same and first andsecond outlets 526 and 527. When the knob 524 is turned to the "on"position, gas is supplied through the outlet 526 to the inlet 528 of amanually operated normally closed valve 529 which is provided with apushbutton 531. At the same time, gas is supplied from the outlet 526 tothe inlet 532 of a normally open flow oscillator cartridge 533. Gas issupplied from the outlet 534 of the cartridge 533 to the inlet 536 of anormally open timing oscillator reset cartridge 537. Gas is alsosupplied from the outlet 534 through an oscillator inspiratory isolationcheck valve 538 to an inlet 539 of an oscillator inspiratory time on theneedle valve assembly 541. Gas flows through the valve assembly 541 at acontrolled rate through the outlet 542 to the inlet 543 an expiratorytime off needle valve assembly 544. Gas is also supplied to the servoport 546 of the flow oscillator cartridge 533. Gas is also supplied fromthe outlet 534 to the inlet 547 of an oscillatory amplitude needle valveassembly 548. Gas is supplied at a controlled rate through the outlet549. The outlet 549 is connected to an outlet fitting 551. The outletfitting 551 has mounted therein an inlet fitting 552. The inlet fitting552 is connected to the venturi jet 553 of a venturi manifold assembly554 that forms a part of the breathing circuit 556 of the type generallydescribed in conjunction with FIG. 5. As disclosed therein, thebreathing circuit 556 also includes a shrouded venturi assembly 557. Theventuri assembly 557 has a venturi like passageway 559 through which thejet of gases from the venturi jet 553 passes. The shrouded venturiassembly 557 is adapted to be connected by a patient adapter 559 to thepatient airway 561. The breathing circuit 556 also includes anexhalation valve assembly 562 of the type hereinbefore described. At thesame time gas is also supplied to the exhalation valve assembly to movethe same to a closed position.

Operation of the flow oscillator cartridge 533 is regulated by theoscillator timing circuit as hereinafter described. Gas flowing from thenormally open flow oscillator cartridge 533 servoes the diaphragm of thetiming oscillator reset cartridge 537 to move it to a closed position.At the same time, gas is being supplied to the servo port 536 of theflow oscillator cartridge 533 to the oscillator inspiratory time onneedle valve assembly 541 at a controlled rate as determined byadjustment of the oscillatory inspiratory time on needle valve assembly541. As soon as the flow oscillator cartridge 533 is servoed to a closedposition, the flow of gas to the flow oscillator cartridge 533 isterminated. This interrupts the flow of gas to the venturi jet 553 andinto the airway of the patient.

The termination of flow through the flow oscillator cartridge 533permits the timing oscillator reset cartridge 537 to return to itsnormally open position. As soon as this occurs, gas behind the diaphragmof the flow oscillator cartridge 533 is bled off through the oscillatorinspiratory time off needle valve assembly 544 through an outlet 563 toan inlet 564 of the timing oscillator reset cartridge 537 and through anoutlet 566 since the cartridge 537 is now in its normally open positionto an inlet 567 of a normally open interval phasing cartridge 568. Gaspasses through the outlet 469 to an outlet fitting 571. An inlet fitting572 is mounted in the outlet fitting 571 and is connected to the inlet573 of a manually operated remote cycling valve 574. The valve 574 isprovided with a pushbutton 576 for manual operation of the same. Thevalve 574 is provided with an outlet 577 which is open to ambient whenthe pushbutton 576 is depressed. The valve 574 is also connected to alarge tube 578 which is connected to the venturi manifold assembly 554.Thus it can be seen that when the flow oscillator cartridge 533 isclosed and interrupts the flow of gas to the venturi jet 553, theexhalation valve 562 is permitted to open and gas from behind thediaphragm of the flow oscillator 533 is emptied to atmosphere throughthe venturi manifold assembly 554 through the expiratory gate 579 oralternatively through the exhalation valve assembly 562. As soon assufficient gases have been bled out from behind the diaphragm of theflow oscillator 533, the flow oscillator 533 moves to its normally openposition to permit the flow of gas through the flow oscillator 533 inthe manner hereinbefore described to again cause gases to flow throughthe venturi jet 553 and to cause closing of the exhalation valveassembly 562.

The rate of oscillation (opening and closing) of the oscillator flowcartridge 533 is determined by adjustment of the oscillator inspiratorytime on and the oscillator expiratory needle valve assemblies 541 and544. Inspiratory/expiratory ratios of various proportions in eitherdirection can be established to provide the desired type of diffusive orvolumetric exchange in the delivery of gas to the patient airway. Theamplitude of oscillatory gases delivered to the patient airway iscontrolled by metering gas at the desired rate through the oscillatoryamplitude needle valve assembly 548. Oscillatory rates of over 25 Hertzcan be programmed with stroke volumes decreasing with rate.Reciprocally, volumetric oscillation rates of one oscillation per minuteor less can be set up with unlimited optional stroke volumes. Duringdiffusive ventilatory protocols at rates of over 100 cycles per minute,mechanical mixing and diffusion serve to homogenite intrapulmonary gasesto more effectively control partial pressures of oxygen and CO₂ in thearterial blood.

The proximal airway pressure rise for each oscillation is under thecontrol of the oscillatory amplitude metering valve 548 that determinesthe rate of flow to the downstream venturi jet 553. The peak pressurewhich will be encountered by the physiological structures, i.e. thepatient airway, is determined by the gross resistance to flow downstreamof the shrouded venturi assembly 557, the pressure drop across theventuri jet 553 and the resistance to entrainment of air by the shroudedventuri assembly 557. The pressure will rise until a full stall(pneumatic clutching) occurs within the ungated venturi assembly 557.Therefore, the peak successive oscillation pressure buildup iscontrolled by pneumatic clutching with the ungated shrouded venturiassembly 557 being referenced to ambient.

With this embodiment of the ventilator, an oscillatory demand CPAP canbe established for a patient at a selected frequency between 3 to 15centimeters of H₂ O. This can be readily accomplished by establishingthe ratio between the inspiratory and expiratory times. By decreasingthe expiratory time, the CPAP is increased and conversely by decreasingthe expiratory time the CPAP is decreased so that in effect there isprovided an oscillatory pattern of pulses at a selected CPAP which isprovided by the pneumatic clutching of the shrouded venturi assembly557. In this way, the patient must exhale against the establishedoscillatory pressure. When the patient wishes to breathe on demand, thepatient can in hale gases in the manner hereinbefore described. In thismanner, the patient receives a controlled mean intrathoracic pressurerise increasing the patient's functional residual capacity. Thefrequency of oscillation and the amplitude of oscillatory stroke volumeprovides the desired mechanical mixing and diffusion of gases within thepatient's lungs.

At the time that gas is supplied from the outlet 534 to the inlet 536the diaphragm of the timing oscillator reset cartridge 537 is moved to aclosed position to again permit servoing of the diaphragm of the flowoscillator cartridge 533 to a closed position.

Mechanical means of frequency band control beyond mechanical metering ofthe flow oscillator cartridge 533 can be accomplished by connecting ametering orifice of a suitable size such as 0.024 inches between thepoint F in FIG. 6 connected to the outlet 536 of the timing resetcartridge 537 and the point G connected to the outlet 581 of theoscillatory amplitude needle valve assembly 548 and also connected to anoutlet fitting 582. The outlet fitting 582 has mounted therein an inletfitting 583 which is connected to a venturi jet 584 of a nebulizer 586.The neublizer 586 can be of the type described in U.S. Pat. No.3,172,406. The nebulizer 586 is connected by a tube 587 into the tube578 connected to the venturi manifold assembly 554. An entrainment gate584 is mounted on the neublizer 586 to permit ambient air to beentrained into the neublizer when necessary. By providing the orificebetween points F and G, it can be seen that gas is purged from behindthe diaphragm of the timing oscillator reset cartridge 537 which asshown is through the nebulizer 586 and then to ambient. If desired theconnections can be omitted and the orifice can bleed directly toambient. This bleed down of the space behind the diaphragm of the timingoscillator reset cartridge 537 is occurring during the time that thediaphragm of the flow oscillator cartridge 533 is being unloaded formovement towards a closed position. An increased rate of diaphragmunloading of the timing oscillator reset cartridge 537 increases theopening rate of the reset cartridge providing for a more rapid cyclingor oscillation. Oscillatory rates approaching 30 Hertz can be obtainedwith a large orifice.

Interval phasing (oscillation on/off) is accomplished by manual means. Aremote cycling valve 574 is operated by the patient. The valve 574 is inits normally closed position and timing gases cannot be purged from theoutlet 566 of the timing oscillator reset cartridge 537 and thereforetiming gases are effectively locked up in the flow oscillator cartridge533 of the timing circuit. This causes the oscillator flow cartridge 533to remain closed (non oscillating).

When the patient pushes in the pushbutton 576 of the manual cyclingvalve 574, gases are purged to ambient from the oscillator flowcartridge 533 through the interval phasing cartridge 568 startingoscillation of the flow oscillator 533 and delivery of gases to theventuri jet 533 and to the nebulizer 586. When the lugs are sufficientlyventilated with repetiative oscillatory aerosolized stroke volumes andassociated pressure rise, the patient releases the manual pushbutton 576and exhales to the ambient through the exhalation valve assembly 562. Agradual decrease in oscillatory rate and amplitude occurs when thepushbutton 576 is released which causes a gradual reversal of mass airflow from the patient pulmonary structure minimizing tendencies fordiffuse physiological airway collapse. This delay can be varied bycontrolling the rate of bleed down through the needle valve assembly 544and through the intervalphasing cartridge 568.

As hereinebefore described, the outlet 526 of the manual on/off switch524 is connected to the manual inspiration valve 529. The manualinspiration valve 529 is provided with the pushbutton 531 which makes itpossible for the clinician to totally override and space all phasicrespiratory functions with the ventilator. Source gas is supplied fromthe outlet 526 through the outlet 591 which is connected to the outletfitting 551 and which in turn is connected to the venturi jet 553.Continued holding in of the pushbutton 531 delivers non-metered flow tothe venturi jet 553 to cause flow into the patient airway to occur untilthe pushbutton 531 is released. The patient can then exhale with theinspiration beginning again when the pushbutton 531 is depressed.

Phasic cycling of the ventilator below 100 cycles per minute can beestablished by the addition of a reservoir (not shown) capable ofcontaining gas installed between the point D which is connected to theoutlet 543 and point E which is connected to the outlet 542. By theaddition of this optional reservoir, the volume which must be filled tocause the diaphragm of the flow oscillator 533 to be servoed closed willbe lengthened to provide the lower frequency of oscillation desired.

Means is provided for automatic phasing of the ventilator shown in FIG.6. For this purpose, gas is supplied from the outlet 521 of the masteron/off switch 523 through timing isolation check valve to an inlet 597of a normally open timing cartridge 598. The outlet 599 of the timingcartridge 598 is connected to an inlet 601 of a timing manifold 602. Gasfrom the timing manifold 602 is distributed through an outlet 603 to aservo port of the interval phasing cartridge 568. Gas is also suppliedto the outlet of the servo isolation check valve 606. Gas is suppliedfrom the manifold 602 to the outlet 607 through the servo port 608 on anormally open timing reset cartridge 609. Gas is supplied from theoutlet 611 to the master timing isolation check valve 612. Outlet 613 isconnected to a fixed reservoir refill orifice 614 of a predeterminedsize such as 0.024 inches. Gas supplied to the timing isolation checkvalve assembly 612 passes through the same, and into the inlet 616 ofthe volumetric exchange (closed exhalation) needle valve assembly 612.Gas at a controlled rate is supplied at the outlet 618 of the needlevalve assembly 617 to the inlet 619 of the diffusion interval (openinspiration) needle valve assembly 612 where the gas is again meteredand supplied through an outlet 622 to an inlet 623 on the open timingreset cartridge 609. Gas is supplied from an outlet 624 into an outletfitting at 626 which is adapted to be connected to an entrainmentreservoir (not shown) of the type hereinbefore described. Gas from theoutlet 618 also flows into a low frequency timing reservoir 627. Theentrainment reservoir is connected to the servo port 628 of the timingcartridge 598.

Patient airway pressure is measured by a gauge 631 which is connectedthrough an adjustable gauge orifice 632 to an outlet fitting 633. Aninlet fitting 634 is mounted in the fitting 633 and is connected to theshrouded venturi assembly 557 so as to be open to the patient airwaypressure.

Operation of the embodiment of the ventilator shown in FIG. 6 whichutilizes automatic phasing may now be briefly described as follows.Source gas from the master on/off control switch 523 passes through thetiming cartridge 598 and charges the timing manifold 602. Gas is meteredthrough the volumetric exchange (closed isolation) needle valve assembly617. Gas entering the timing cartridge cannot exit through the diffusioninterval metering valve 621 because the timing reset cartridge has beenservoed to a closed position. Therefore the timing circuit ispressurized at a rate controlled by the volumetric exchange (exhalation)metering valve 617 until the pressure acting through the servo inlet 628of the timing cartridge 598 is sufficient to servo the diaphragm offclosing the normally open cartridge 598 and interrupting the flow of gasthrough the cartridge 598. During the time that there is gas flowthrough the timing cartridge 598, the interval phasing cartridge 568 isservoed into the closed position. The interval phasing cartridge 568receives at its inlet 567 a pulsatile flow from the outlet of the timingoscillator reset cartridge 537. When the out flow from the timingoscillator reset cartridge 537 is obstructed by closing of the intervalphasing cartridge 568, oscillation ceases because of a locked uposcillator timing circuit.

When the timing cartridge 598 closes, gas flow to the timing manifold602 ceases. The manifold 602 is depressurized through the reservoirrefill orifice 614 causing opening of the interval phasing cartridge 568and the timing reset cartridge 609 to again initiate diffusion(inspiratory) level. When the timing reset cartridge opens, thediffusion interval (inspiratory) metering valve 621 starts a bleed downthrough the now open timing reset cartridge 609 of the timing gasesbehind the manifold of the timing cartridge 598 and in the reservoir 627until the timing cartridge 598 moves to its normally open position atwhich time a repetitive cycle commences. From the foregoing it can beseen that the oscillation timing circuit is a slave to the master phasic(interval) timing circuit hereinbefore described.

An overrigiding function can be initiated by terminating the diffusioninterval by loading the timing circuit into the expiratory phase bycharging the timing circuit through the servo isolation check valve 606by connecting it into which an input would be supplied from theinspiratory phase of the ventilator shown in FIG. 3 in which the servoisolation check valve 606 would receive the same penuamtic signal whichis received from the isolation check valve 331 shown in FIG. 3. Thisadditional or overriding function can be a volumetric stroke volume or adiffusive oscillation delivered through the same or a parallel venturijet into the patient airway. This alternative could be used toaccommodate partial pressures of oxygen and carbon dioxide in thearterial blood in the maintenance of the respiratory function of thepatient.

Manual cycling as an override of automatic programmed cycling can beaccomplished by closing the diffisuion interval (inspiratory) meteringvalve 621 and opening the volumetric exchange (expiratory) meteringvalve 617. This causes constant oscillation by keeping the intervalphasing cartridge 568 in a continuously open position. During the timethat automatic cycling is being utilized in the ventilator, the fitting572 should be removed from the fitting 571 so that the fitting 571exhausts to the atmosphere.

When it is described to utilize the remote cycling valve 574, thefitting 572 is mounted in the fitting 571. The valve 574 is normallyclosed and when the pushbutton 576 is depressed, the pulsatile timinggases supplied through the timing oscillator reset cartridge 537 aresupplied through the interval phasing cartridge 568 and are released toambient through the valve 574 to causes the onset of oscillation asprogrammed. Release of the button 576 stops the oscillation.

From the foregoing, it can be seen that with the ventilator disclosed inFIG. 6, three different types of diffusive ventilation of the patientairway can be accomplished at rates of over 100 cycles per minute. Insummary, the operation of the ventilator shown in FIG. 6 can bedescribed as follows. Let is be assumed that it is desired to operatethe ventilator manually. When this is the case, the fitting 572 isinserted into the fitting 571. In addition, the diffusion intervalmetering valve 621 should be moved to the totally closed position andthe volmetric exchange metering valve 617 should be moved to the totallyopen position. This serves to move the timing cartridge 598 to a closedposition which prevents servoing the interval phasing cartridge 568 toits closed position and thus ensures that the oscillator timing circuitis under the control of the remote cycling valve 574. When this is thecase it can be seen that by depressing the pushbutton 576 of the remotecycling valve 574, the oscillator timing gases will bleed off to ambientand will permit the flow oscillator cartridge 533 to oscillate under thecontrol of the metering valves 541 and 544 as hereinbefore described.This causes gases to be supplied to the venturi jet 553 to the patientairway to supply gas at a predetermined frequency and pressure asdetermined by the setting of the metering valves 541 and 544 and theoscillatory amplitude metering valve 548 to thereby provide pulsatilegases at a predetermined pressure in the patient airway. During the timethis is occurring, the patient can still exhale at a predeterminedpressure through the shrouded venturi 557 and through the expiratorygate provided on the venturi manifold assembly 554. It is possible thatsome of the exhaled gases may pass through the oscillation valveassembly 562 during the negative phase of the pulsatile air flow fromthe flow oscillator 533. As soon as the pushbutton 576 of the cyclingvalve 574 is released, pressure will build up because the gases cannotexhaust to the atmosphere through the cycling valve from the timingoscillator reset cartridge 537 and gasses will build up to servo theflow oscillator cartridge 533 to move it to the closed position toprevent further flow of gases into the patient airway. The patient thencan exhale through the exhalation valve assembly 562 as well as throughthe expiratory gate provided in the venturi jet manifold 554. Pulsatilegases can be again introduced into the breathing circuit of the patientby depressing of the button 576.

Now let it be assumed that instead of manual phasing of the gases to thepatient airway it is desired to have this accomplished automatically.This can be done by opening the volumetric exchange metering valve 617to the desired position and closing the diffusion interval needle valve621 to the desired position to provide the desired phasic cycling. Themetering valve 617 determines the time "off" whereas the metering valve621 determines the time "on". In addition the fitting 572 should bedisconnected from the fitting 571 so that the oscillator timing gasesare exact to the atmosphere through the fitting 571. Gases supplied tothe patient will be pulsatile gases in the same manner as under manualoperation. The patient will still be able to exhale any time even thoughpulsatile gases are being delivered to the patient and during the timethat pulsatile gases are not being delivered to the patient in themanner hereinbefore described.

In FIG. 6A there is shown an oscillator circuit which can be utilized toreplace the oscillator circuit in FIG. 6 which would include the flowoscillator cartridge 533, the timing oscillator reset cartridge 537, theinterval phasing cartridge 568, the oscillator inspiratory meteringvalve 541, the oscillatory amplitude metering valve 548, the oscillatorinspiratory isolation valve 538 and the oscillator expiratory meteringvalve 544. In their place would be substituted the circuitry shown inFIG. 6A which would be connected between point A which is connected tothe outlet 603 of the timing manifold 602, and point B which would beconnected to the outlet 526 of the master on/off switch 523 to providesource gas under pressure and point C which is connected to the outlet549 of the oscillatory amplitude metering valve 548 and another terminalD which is connected to the outlet fitting 626. Source gas is supppliedfrom the master on/off switch to the outlet 526 to the terminal B and tothe inlet 641 to a normally open expiratory differential oscillatorcartridge 642. The gas is supplied to an outlet 643 to an inlet 644 ofan oscillation frequency rate metering valve 646. The metered flow ofgas passes through an outlet 647 to a servo port 648 of the expiratorydifferential oscillator cartridge 642. At the same time, gas flow fromthe outlet 643 is supplied to the inlet 649 of a normally openinspiratory interrupter cartridge 651. Gas is supplied to an outlet 652to an inlet 653 of an oscillator flow and secondary rate controlmetering valve 654. The metering valve 654 is provided with an outlet656 for the main flow of gas to the venturi socket 551 and into theventuri jet 553 to the patient airway. Gas is also supplied by themetering valve 654 through an outlet 657 which is connected to theoutlet fitting 626 that is connected into the reservoir (not shown).This commences the buildup of the pressure pulse. As soon as there hasbeen sufficient pressure buildup behind the diaphragm of the expiratorydifferential oscillator cartridge 642, it is moved to a closed positionto terminate the flow of source gas through the cartridge 642. As soonas this occurs, gas behind the diaphragm of the expiratory differentialoscillator 642 will bleed in a reverse direction through the oscillationfrequency rate metering valve 646 which will be supplied to the inlet649 through the normally open inspiratory interrupter cartridge 651through the outlet 652 through the metering valve 654 and through theventuri socket 651 to the patient airway which is open to ambientthrough the exhalation valve assembly 562. As soon as there has beensufficient bleed down of gases, the expiratory differential oscillator652 moves to its normally open position to permit source gas again toflow through the same to restart the cycle for the next pulse.

Now let it be assumed that it is desired to utilize the ventilatorcircuitry shown in FIGS. 6 and 6A in conjunction with a conventionalrespirator of the type described in the U.S. Pat. No. 4,060,078 which isprovided with an inspiratory phase and an expiratory phase in itsoperative cycle. The terminal A of the circuit shown as FIG. 6A would betied into a point in the conventional respirator in which it would sensethe inspiratory flow of gases to the patient. When this occurs, theinspiratory flow would pass through a servo isolation check valve whichis connected to the servo port 662 of the inspiratory interruptercartridge 651. As soon as the diaphragm is pressurized, the inspiratoryinterrupter cartridge is moved to a closed position to terminate theflow of timing gases from the expiratory differential oscillator 642.The amount of time in which the inspiratory interrupter cartridge ismaintained in a closed position is determined by the flow of gasesthrough an oscillator delay and anti-surge metering valve 663 which hasits inlet 664 connected to the servo inlet 662. It has an outlet 666which is connected to the reservoir socket 626. Thus it can be seen thatas soon as the pressure behind the diaphragm of the inspiratoryinterrupter cartridge 651 is bled down sufficiently, it will move to anopen position to again permit the flow of oscillatory gases from theexpiratory differential oscillator 642. In this way, it is possible toimpose oscillatory pulsatile gas flow on to the main gas flow providedby the conventional respirator. By appropriate adjustment of the vale664 it is possible to ascertain the positioning of the pulsatile gasesonto the main gas flow from the conventional respirator.

Now let it be assumed that the circuitry shown in FIG. 6A has beenconnected to point A shown in FIG. 6 in which the timing circuit of FIG.6 is utilized in conjunction with the oscillator shown in FIG. 6A. Whenthis is the case, as soon as a gas is supplied from the timing manifold602 through the servo isolation check valve 661, the inspiratoryinterrupter cartridge 651 will be moved to a closed position toterminate the pulsatile flow of gases and also the pulsatile flow isterminated for a period of time which is determined by the time requiredto load the diaphragm of the timing cartridge 598 by gases passingthrough the volumetric exchange metering valve 617. As soon as thetiming cartridge 598 moves to a closed position, the pressure in thetiming manifold will drop to atmospheric through the reservoir refillorifice 614 by unloading the diaphragm in the timing reset cartridge 609to permit it to move to an open position. As this occurs, the diaphragmof the timing cartridge 598 can be unloaded by gas bleeding through thediffusion interval metering valve 621 through the timing reset cartridge609 into the reservoir socket 626.

While the space behind the diaphragm of the timing cartridge 598 wasbleeding won, there was no flow of gas through the servo isolation checkvalve 661 but the gases behind the diaphragm of the inspiratoryinterrupter cartridge 651 will be bled down through the oscillator delayand anti-surge metering valve 663. As soon as this occurs, pulsatilegases will again be delivered to the patient airway. The desired mode ofoperation would be for the oscillator delay and antisurge metering valve663 to time out prior to timing out of the diffusion interval meteringvalve 621 to prevent the delay provided by the metering valve 663 to bemore than the delay provided by the diffusion interval metering valve621 and thereby ensure that oscillation will always take place.

In FIG. 6B there is shown an optional breathing circuit which can beutilized in place of the breathing circuit shown in FIG. 6. It consistsof a nebulizer 586 of the type hereinbefore described. It also includesa tri-jet venturi assembly 671. The tri-jet venturi manifold 671includes a central jet 673 surrounded by two additional jets 674 and676. The central jet 674 would be supplied with the pulsatile gas flowsupplied from the outlet socket or fitting 551. The other jets 674 and676 could be supplied with inspiratory flow from a conventionalrespiratory or in addition could be provided with a constant flow of gasfrom CPAP flow from a conventional respiratory. The breathing circuitshown in FIG. 6B also includes an exhalation valve assembly 678 of aconventional type. The exhalation valve assembly 678 is provided with aninlet 679 which is supplied oscillatory gases from the venturi socket551 so that it is moved to a closed position during the initiation of apulse of gas. The inlet 679 is also connected to a metering valve 681which opens to the atmosphere. This bleed off of gases provides a slightdelay in the closing of the exhalation valve so as to partially delaythe buildup of pressure within the patient airway at the commencement ofa pulse of gas being supplied to the patient airway.

The breathing circuit shown in FIG. 6B also includes a subambientventuri assembly 683. This subambient venturi assembly 683 consists of acylindrical body 684 which has a venturi-like passage 686 formedtherein. One end of the body 684 is open to ambient whereas the otherend has mounted therein a venturi jet 687 disposed in such a manner sothat gases exiting from the jet will pass through the venturi passage686. The venturi jet 687 is connected to a suitable source of gas suchas a constant flow of gas or an intermittent flow of gas to provide thepressure drop within the venturi which is communicated by a tube 688 tothe exhalation valve outlet port to supply a negative pressure to theunderside of the diaphragm of the exhalation valve and to apply anegative pressure to the patient airway during the time that theexhalation valve is in an open position. The shrouded venturi 672 isprovided with a fitting 689 which can be connected to the airwaypressure gauge 631 to permit monitoring of the pressure in the patientairway.

Still another embodiment of the ventilator of the present invention isshown in FIG. 7. This also can be characterized as an intermittantpercussive ventilator which is particularly adapted for home respiratoryuse. As will be seen as hereinafter described, it includes an oscillatorcircuit very similar to that described in the embodiment shown in FIG.3.

A source of gas 701 is provided which is supplied to an outlet 702. Thesource of gas 701 can be a source of air or alternatively a source ofair mixed with oxygen as supplied by a blender of the type hereinbeforedescribed. Gas supplied to the outlet 702 is connected to the inlet 703of a rotary master on/off switch 704 which is provided with a controlknob 706. The switch 704 is provided with an outlet 707 which isconnected to the inlet 708 of a normally closed manual inspiration valve708. The valve 708 is provided with a pushbutton 709 for moving the sameto an open position to supply gas through an outlet 711 which isconnected to a venturi socket 712. A fitting 713 is provided formounting in the socket 712 and is connected to a nozzle or a jet 714carried by a manifold 716. The manifold 716 is part of a breathingcircuit 717 and is mounted on a shrouded venturi assembly 718 of thetype hereinbefore described in connection with previous embodiments. Theshrouded venturi assembly 718 is adapted to be connected to the patientairway 710 is the manner hereinbefore described. An exhalation valveassembly 721 is mounted on the shrouded venturi assembly and has aninlet 722 which is connected to the fitting 713 so that when gas issupplied to the nozzle 714, gas is also supplied to the inlet 722.

Source gas is also supplied from the outlet 706 to an inlet 724 of anormally open flow oscillator cartridge 726. Gases are supplied from theoutlet 727 through an inspiratory isolation check valve assembly 728 toan inlet 729 of the oscillator inspiratory time on metering valve 731.Metered gas flow is supplied through an outlet 732 to a zero port 733for the flow oscillator cartridge 726. Gas is also supplied rom theoutlet 732 to an inlet 734 of an oscillator expiratory time off meteringvalve 736 which is provided with an outlet 737. The outlet 737 isconnected to an inlet 738 of a normally open oscillator timing resetcartridge 739 and to an outlet 741. The outlet 741 is connected to amanual cycling socket 743. A fitting 743 is adapted to fit within thesocket 742 and is connected to the inlet 744 of a manual cycling aerosolcontrol switch 746 of the type hereinbefore described in conjunctionwith FIG. 5. It is maintained in a normally closed position and isprovided with a pushbutton 747. The switch 746 forms a part of anebulizer 748 of the type hereinbefore described in conjunction withFIG. 5. The switch 746 is mounted on the shrouded venturi assembly 718in such a manner so that when the pushbutton 747 is depressed, theoutlet 741 is in communication with the patient airway whichperiodically is open to ambient through the exhalation valve assembly721.

Gas is also supplied from the outlet port 728 of the oscillatorinspiratory time on cartridge 727 to the inlet 751 of an oscillatoryamplitude metering valve assembly 752. Metered gases from the meteringvalve 752 are supplied through an outlet 753 which is connected to theventuri socket 712. Gas from the outlet 728 is also supplied to theservo port 754 of the oscillator time reset cartridge 379. The servoport 754 is also connected to the range compensator orifice 756 which isconnected to a nebulizer socket 757. A fitting 758 is mounted in thenebulizer socket 757 and is connected to the venturi jet or nozzle 758of the nebulizer 748.

Means is provided for sensing the airway pressure of the patient andconsists of a gauge 761 which is connected through an adjustable gaugeorifice 762 to a socket 763. A fitting 764 is provided for the socket763 and is connected to a fitting 766 provided on the shrouded venturiassembly 718.

The valve 708A is provided with an outlet 710 which is connected throughan orifice 711 of a suitable size such as 0.035 inches to a venturisocket or fitting 712. The orifice 711 is provided to ensure that amaximum pressure of approximately 40 centimeters of water is supplied tothe airway of the patient from a 50 psi source.

Operation of the oscillator 699 in communication with the breathingcircuit 717 may now be briefly described as follows. Let us assume thata patient at his home desires to utilize the same in connection withadministering a certain drug which is placed within the nebulizerassembly 748. When the patient is ready to use the same, the breathinghead can be connected to the airway of the patient in a suitable mannersuch as by the use of a mouthpiece. The knob 706 is turned on and thenthe pushbutton 747 is depressed. As soon as the pushbutton 747 isdepressed oscillation of the oscillator circuit 699 commences to providepulsatile gases through the fitting 712 to the venturi nozzle 714 intothe airway of the patient while at the same time delivering gas to thenebulizer 748 through the socket 757 so that an aerosol containing thedrug carried by the nebulizer is brought into the circumferential areasin the shrouded venturi assembly 718 so that it is also delivered to theairway of the patient and mixed with gas which is introduced through thecentral venturi.

Oscillation occurs in the same manner as described in conjunction withthe embodiment shown in FIG. 3. As source gas is delivered to the flowoscillator 727 gas is supplied at the output 728 and gas passes into therange compensator orifice 756 and also through the oscillatory amplitudemetering valve 752 into the venturi socket 712 into the venturi jet 714into the airway of the patient. As soon as the flow passages have beenoverwhelmed pressure builds up in the servo port 754 of the oscillatortiming reset cartridge 739 to move to a closed position. In addition,gas is supplied from the outlet 728 into the timing circuit through theexpiratory isolation check valve 728 to the oscillator inspiratory timeon metering valve 731 into the servo port 733 of the flow oscillatorcartridge 727. This servos that diaphragm to move the cartridge to aclosed position to interrupt the flow of gas from the outlet 728. Assoon as the source gas is interrupted to the servo port 754, gas behindthe diaphragm in the oscillator timing reset cartridge is bled downthrough the oscillator amplitude metering valve 752 into the airway ofthe patient to ambient through the exhalation valve assembly 721. Atthis time, air also bleeds out of the servo port 733 for the flowoscillator cartridge 727 through the outlet 734 of the oscillatorexpiratory time off metering valve 736 through the outlet 737 and intothe inlet 738 of the oscillator timing reset cartridge 739 which is nowin the open position through the outlet 741 through the manual cyclingsocket 742. It there has been inadequate buildup of pressure in thelines leading to the manual valve 746, the flow oscillator cartridge 727will move to an open position permitting gas to flow from its outlet 728to again cause source gas to flow through the venturi socket 712 to theairway of the patient. The same cyclic action takes place until therehas been a sufficient buildup of gas in the lines leading to the manualcycling aerosol control valve assembly 746 so that the diaphragm of theflow oscillator 727 will not move to an open position. When this occursthen further oscillation will cease.

It generally has been found that approximately two oscillations willoccur before there has been a sufficient buildup in the lines leading tothe manual cycling aerosol control valve assembly 746. Thereafter,oscillatory action can only be commenced by depressing the button 747 ofthe control switch 746 which empties the gases from the lines leadingfrom the oscillator timing reset cartridge 739 into the venturi assembly718 and into the patient airway. As soon as this occurs, the gaspressure behind the diaphragm in the flow oscillator 727 will be bledout through the oscillator expiratory time off metering valve 736through the oscillator timing reset cartridge and through the manualcycling aerosol control valve 746 to start the oscillatory actionhereinbefore described causing pulses of gases to be continued to besupplied to the airway of the patient as long as the pushbutton 747 ofthe manual cycling aerosol control valve is depressed. An aerosol willbe dispensed into the airway of the patient during the time thepushbutton 747 is depressed. There is supplied to the patient airway gasunder pressure upon which there is superimposed pulses of gases with theoscillation of the flow oscillator cartridge 747. When the pushbutton747 is released approximately two additional oscillations will occuruntil there has been a sufficient buildup of pressure within the linesleading to the control valve 746 to stop the oscillation of theoscillator circuit 699 hereinbefore described. There additional pulsesthe pushbutton 747 is released cause a gradual decrease in the airwaypressure and prevent against possible airway collapse which couldpossibly occur in the event of a sharp pressure drop in the proximalairway.

In FIG. 7A there is disclosed a schematic diagram of an optional circuitwhich can be utilized in conjunction with the ventilator shown in FIG. 7to permit the ventilator in FIG. 7 to be selectively employed as eithera volumetric or a diffusive device. This optional circuit consists of anoscillator-type cycle selector switch 767. This switch 767 is providedwith an inlet port 767a which is adapted to connected to the ports 732and 733 in FIG. 7. It is also provided with a slidable valve member 768which can be manually positioned in either of two positions to permitflow either through an outlet port 767b or through an outlet port 767c.Gas flow through the outlet port 767b flows into a rate reductionisolation check valve 770 to the port 734 in FIG. 7. The outlet port767c is adapted to be connected directly to the port 734.

When the slidable valve 768 is moved to the left as viewed in FIG. 7A,gas will flow from the inlet port 767a through the outlet port 767cdirectly into the port 734 to permit operation of the ventilator asshown in FIG. 7 in the manner hereinbefore described. However, when theselector valve 768 is moved to the right as viewed in FIG. 7A, gas willno longer flow through the port 767c but will flow through the port 767bthrough the rate reduction reservoir 769 and through the reductionisolation check valve 770 to the port 734. This converts the deviceshown in FIG. 7 from a diffusive device to a volumetric respirator orventilator. By connecting the reservoir 769 into the servo port 733, theservoing bleed down times are substantially increased so that theventilator shown in FIG. 7 no longer acts as a diffusive respirator orventilator but acts as a volumetric ventilator with cyclic rates below100 cycles per minute.

From the circuitry shown in FIG. 7A it can be seen that the relativelysimple ventilator which is shown in FIG. 7 can be programmed for eithervolumetric or diffusive ventilation manually by operation of theselector switch 767. This makes it possible for a ventilator such asshown in FIG. 7 as modified with the circuitry shown in 7A to permit thepatient to be stabilized on diffusive ventilation and thereafterswitched over to volumetric ventilation to conserve oxygen suppliesduring transport where the oxygen supply may be minimal. Thus, it can beseen that the modification shown in FIG. 7A can be utlized inconjunction with the ventilator of FIG. 7 to provide percussive therapy.diffusive and/or volumetric ventilation for critical care as well as forother conventional uses for ventilators.

In FIG. 8 there is shown a decompression expiratory oscillation modulewhich can be utilized with the ventilator which is shown in FIG. 3. Itis provided with terminals A and B which are adapted to be connectedinto the points A and B shown in FIG. 3. As can be seen, point A isconnected into the source of oxygen for the ventilator shown in FIG. 3whereas connection B is connected into the outlet 24 from the oxygenblender 21.

The decompression and expiratory module 771 consists of a body 772 whichhas an aneroid 773 mounted therein which is exposed to ambient throughan opening 774 and which is referenced to seal level. The aneroid 773 isconnected to a valve stem 776. The valve stem 776 carries a valve member777 which is adapted to be moved between open and closed positions withrespect to a valve seat 778 formed in the body 772. The valve member 777is yieldably urged towards a normally closed position by a spring 779carried by the body 772. The body 772 is provided with an inlet 781which is connected to the terminal A and as hereinbefore explained isconnected to the oxygen source. The body 772 is also provided with anoutlet 782 which is connected to the outlet 24 of the oxygen blender 21.

Let it be assumed that the ventilator with the decompression andexpiratory oscillation module 771 is carried by a transport vehicle suchas an aircraft flying at an elevation of 35,000 feet. Let it also beassumed that there has occurred on the aircraft an explosivedecompression bringing about a pressure differential which can be asgreat as 9 psi. This pressure differential is immediately sensed by theaneroid 774 which expands and moves the valve member 777 to an openposition to immediately permit oxygen to enter from the oxygen sourceinto the outlet line connected to the outlet 24 of the oxygen blender sothat there is a supply of 100 percent oxygen through the ventilator foruse by the patient who has encountered this explosive decompression.

In FIG. 9 there is disclosed an automatic aneroid decompression reliefvalve assembly 786. It consists of a cylindrical body 787 which has ananeroid 788 mounted in one end of the same which is exposed to ambientthrough an opening 789 provided in the body 787. The aneroid 788 isreferenced to sea level. The aneroid 788 is connected to a valve stem791 which carries a valve member 792 that is adapted to be moved betweenopen and closed positions with respect to a valve seat 793 carried bythe valve body 787. The body 787 is provided with a fitting 794 which isconnected to a large tube 796 that is adapted to be connected to theshrouded venturi assembly 323 shown in FIG. 3 in such a manner so thatthe tube 796 is connected at the head of the venturi-like passagewayprovided in the venturi assembly. The body 787 is provided with anadditional annular valve seat 798 which is adapted to be engaged by avalve member 799. The valve member 799 is carried by valve stem 801. Anarmature 802 is mounted on the end of the valve stem and is adapted tobe attracted by magnets 803 carried by the body 787. The body 787 isprovided with an opening 804 which is open to the atmosphere.

Again assuming that the ventilator is being carried by a transportvehicle such as an aircraft flying at 30,000 feet and also assuming thatan explosive decompression is encountered, it can be seen that theaneroid 788 will sense this decompression in the manner hereinbeforedescribed and will move the valve member 792 towards an open position.This will vent the gases from the airway of the patient towards the gatevalve member 799 to move it towards an open position against the forceof the magnets attracting the armature 802 to vent the tube 796 toambient through the opening 804. The gate valve member 799 serves toretain a governed pressure determined by the magnetic forces which areapplied to the magnet 802 as for example a pressure of 20 centimeters ofwater. As flow increases through the gate valve 799 and through theopening 804, the magnetic forces attracting the armature 802 are reducedpermitting an explosive flow of gas from the lung to thereby preventpneumothoracy. Thus it can be seen that with the decompression andexpiratory oscillation module provided in FIG. 7A and the automaticaneroid decompression relief valve assembly 86 there is provided meansfor accommodating an explosive decompression on an aircraft withoutendangering the life of the patient on which the ventilator is beingutilized.

In FIG. 10 there is disclosed a pneumatic exhalation valve assemblywhich can be utilized with the various embodiments of the ventilatorshereinbefore described. By way of example, it could be utilized in theventilator shown in FIG. 7 in which it would be substituted for theventuri manifold 716, the shrouded venturi 718 and the exhalation valveassembly 721.

The exhalation valve assembly 816 shown in FIG. 10 consists of agenerally cylindrical hollow body 817 which has a cylindrical passage818 extending therethrough. An expiratory outlet 819 is mounted in thebody 817 and is in communication with the passage 818. An additionaloutlet 821 is in communication with the passage 818 and is mounted inthe body to extend diametrically therefrom and is utilized for samplingthe airway pressure within the passage 818. The outlet 821 as shown isthreaded into the body 817 and an O-ring 822 is provided to form anair-tight seal with the body. The passage 818 terminates in a proximalairway port 823 which is adapted to receive a suitable patient adaptersuch as a mouthpiece or endotracheal tube to be connected into thepatient airway. A generally cylindrical venturi body 826 is provided andis sized in such a manner so that it can be slidably mounted within thepassage 818 of the body 817. The body 817 is mounted within acylindrical venturi bushing 827 in such a manner so that the bushing 827moves with the venturi body 826. The venturi body 826 is provided withan annular flange 828 at its forward extremity which engages the forwardextremity of the bushing 827. It is also provided with a centrallydisposed annular flange 829 which also frictionally engages the bushing827. At its rearmost extremity, the body 826 is provided with anotherannular flange 831 which engages a lip 832 that is L-shaped in crosssection provided on the rear extremity of the bushing 827. The venturibody 826 is provided with a venturi-like passageway 833 which extendsaxially of the venturi body and opens through both ends of the venturibody 826. The forward extremity of the venturi body is provided with achamber 834 in which a main inner groove 836 is provided and in whichthere is seated an O-ring 837. The O-ring 837 serves as a valve memberand is adapted to engage a conical valve seat 838 which is formed in thebody 817 immediately ahead of the expiratory outlet 819.

Means is provided for yieldably urging the venturi body 826 with itsassociated bushing 827 to a position so that the O-ring valve member 837is moved out of engagement with the valve seat 838 and consists of ahelical spring 841 which has one end seated against the lip 832 providedon the bushing 827 and has the other end engaging an annular abutment842 formed in the venturi body 826.

The venturi body 826 is provided with a cylindrical threaded end 844which has threaded thereon a cylindrical cap 846 which has portions ofthe same cut away to provide openings 847 which are in communicationwith an inlet 848 mounted in the body 817 and also in communication withthe passage 818. The remaining portions of the cap 846 form L-shapedlegs 849 which serve to support a nozzle 851 in a position so that acentrally disposed passage 852 extending therethrough is in axialalignment with the axis of the venturi-like passageway 833 provided inthe venturi body 826. A nozzle or jet 851 is provided within the largercylindrical bore 853 in axial alignment with the passage 852. An annularrecess 854 is formed in the bore 853 and carries an O-ring 856. An endcap 858 is threaded into the outermost rear extremity of the body 817.An annular recess 859 is provided in the body 817 and receives the outerannular margin of diaphragm 861 formed of a suitable material such asneoprene. The diaphragm 861 extends across the inner face of the end cap858 and carries a hollow diaphragm stem 862 having a flow passage 863therein. The stem is adapted to be inserted into the bore 853 of thenozzle 851 and is adapted to establish a sealing engagement with theO-ring 856 so that an airtight seal is formed between the stem 862 andthe nozzle 851. Passage 863 is in alignment and in communication with aflow passage 864 provided in the end cap 858. The end cap is providedwith an inlet fitting 866 which is adapted to receive pulsatile air flowfrom a ventilator of the type hereinbefore described.

Operation of the exhalation valve assembly 816 in ventilators of thetype hereinbefore described may now be briefly described as follows. Letit be assumed that the appropriate connections have been made to theexhalation valve assembly 816 form the ventilator as for example theventilator shown in FIG. 7. Thus the fitting 713 would be connected tothe fitting 866 provided on the end cap 858. The fitting 764 would beconnected to the fitting 821 to provide the patient airway pressure. Nowlet it be assumed that pulsatile gases are being supplied to the venturioutlet 712 of the ventilator shown in FIG. 7. These pulsatile gases aresupplied through the passage 864, through the passage 863, through thenozzle 851, through the bore 846 into the venturi-like passage 833 andthence into the patient airway. As the pressure introduced through thepassage 864 overwhelms the orifice 852 provided in the nozzle 851,pressure is built up behind the diaphragm 861 to move the diaphragm withthe hollow diaphragm stem 862 forwardly carrying with it the venturibody 826 with its associated bushing 827 forwardly in the body 817 untilthe O-ring valve member 837 engages the valve seat 838 provided in thebody to close off the expiratory port or outlet 819. In this manner, theexpiratory port is closed off in the same manner in which the exhalationvalve assembly 721 is moved to a closed position by the application ofair under pressure to the exhalation valve assembly. The advantage ofthe arrangement shown in FIG. 10 is that as soon as gas is no longersupplied to the exhalation valve assembly 816, the spring 841 returnsthe sliding venturi body 826 to its rearmost position determined by therearmost position of the valve stem carried by the diaphragm 861.

It has been found that the combination venturi jet and exhalation valveassembly 816 has numerous advantages over the combination of theshrouded venturi assembly and the exhalation valve assemblies providedin the ventilators hereinbefore described. These advantages includerapid opening and closing of the expiratory port 819 which isaccomplished in view of the fact that the sliding venturi body reactsvery rapidly to the changes in gas pressure behind the diaphragm 861.Thus immediately upon receipt of gas in the nozzle 851, the diaphragm isactuated to move the sliding venturi body forward to close theexpiratory port 819. Conversely, as soon as gas is no longer beingintroduced through the nozzle 851, the spring 841 rapidly returns thesliding venturi body to its original position. This makes possible amuch higher frequency of oscillation with maximum stroke volume with aminimal oscillatory CPAP. An additional advantage is that there is verylittle dead space in the device ahead of the exhalation gate formed bythe O-ring seal 837. This minimizes rebreathing. The device shown inFIG. 10 also has the advantage that only one power source is requiredfor operation of the device whereas in previous embodiments two powersources were required. Another advantage of the device is that in theevent of failure of the ventilator driving the device, the deviceassumes a fail-safe position which permits free breathing to ambientthrough the expiratory port 819. Even if the sliding venturi body 826for some reason should happen to lock up in the closed position, thepatient can still breathe through the venturi-like passageway 833because of the clutching provided by the device. In addition, theexhalation valve assembly shown in FIG. 10 has the advantage in that itautomatically remains in phase with inspiration. In addition, it isfound that the construction of the present exhalation valve assemblyalso serves as a muffler to provide quiet operation of the venturi whichis provided in the device.

Because there is low inertia in the part forming the exhalation valveassembly shown in FIG. 10, it has been found that frequencies as high as30 Hertz can be accomplished without getting out of phase.

In making a comparison between the volumetric ventilation which has beenprovided with ventilators used in the past and the diffusive ventilationwhich is accomplished with the ventilators of the present invention itshould be appreciated that the volumetric ventilators delivered a tidalvolume to the patient which was greater than the sum of the anatomicaldead space in the airway of the patient and the mechanical dead space inthe ventilator. With such volumetric ventilation, a cyclical rate ofbelow 100 cycles per minute was utilized for neonates and cyclical ratesbelow 100 were utilized for children with the rate for adults going downto as low as 10 cycles per minute. By way of example the typical lungcapacity for an adult ranges from 3500 to 5000 milliliters. The tidalvolume delivered to the patient by a volumetric ventilator willtypically be in the range of 500 to 1000 milliliters.

On the other hand, utilizing diffusive ventilation with the ventilatorsof the present invention, successive volumes or stroke volumes orboluses of gas are delivered to the airway of the patient which are onlya small fraction of the sum of the anatomical and mechanical dead spaceand which is only a small fraction of the total lung capacity of thepatient. Thus by way of example for an adult human being having a lungcapacity of 3500 to 5000 milliliters, the stroke volume or boluses ofgas delivered to the airway of the patient under diffusive ventilationwould range from 10 to 75 milliliters for each volume of gas. Inaddition, as a further comparison, the frequency rate of introduction ofthe successive stroke volumes or boluses of gas into the airway of thepatient would always typically be in excess of 100 cycles per minutewhereas with the diffuse ventilation ranging from two to seven Hertz,the equivalent cycles per minute rate is 120 to 420 cycles per minute.Thus it can be seen that the cyclic rate for diffusive ventilation isonly a small fraction of the cyclic rate for volumetric ventilation. Inthe ventilators of the prevent invention, in addition to providingdiffusive ventilation, it is possible either manually or automaticallyto superimpose upon diffusive ventilation, volumetric ventilation bysupplying tidal volumes of gas to the airway of the patient.Alternatively, the diffusive ventilation can be terminated during thetime that the tidal volumes are being delivered to the airway of thepatient.

The ventilators hereinbefore described permit the use of advantagedventilatory concepts which allow most patients requiring ventilatorysupport to breathe spontaneously during long term cardiopulmonarymanagement. Current routine volumetric ventilation with such ventilatorswith volume oriented type delivery frequently requires sedation orrelaxation of the patient to prevent physiological/mechanical conflict.In the ventilators hereinbefore described no provision is made forfail-safe protection to cover the spontaneously breathing patient in theevent of total ventilator failure. The breathing circuit which is shownin FIG. 11 is provided to give fail-safe protection in the event of sucha ventilator failure. The breathing circuit 871 which is shown in FIG.11 can be substituted by way of example for the breathing circuit 266provided in the ventilator shown in FIG. 3.

As shown in FIG. 11, the connections to the breathing circuit 871 arethrough fittings 369, 406, 321 and 312 which are shown in FIG. 3. Thebreathing circuit includes an exhalation valve assembly 872 of the typewhich is shown in FIG. 10. A proximal airway swivel 873 is mounted onthe forward extremity of the exhalation valve assembly 872 and is incommunication with the port 822 provided in the body 817. The proximalairway swivel can be provided with the patient adapter (not shown) whichcan be connected to the patient airway represented symbolically by theballoon 876. The proximal airway swivel 873 is provided with anaspiration port 877 which is normally closed by a plug 878. The outlet821 of the exhalation valve assembly 872 is connected to the fitting 369which is used for monitoring the patient airway pressure. The inlet 848of the exhalation valve assembly has mounted thereon an overpressurefail-safe relief valve 881. The valve 848 of the exhalation valveassembly has mounted thereon and overpressure fail-safe relief valve881. The valve 881 provides pressure relief at a suitable pressure suchas 10 centimeters of H₂ O. The relief valve is provided with an outlet882 which is mounted by a slip fit on the inlet 848. The relief valve881 is provided with an inlet 883 which is connected to a large tub 884which forms a part of the inspiratory side of the breathing circuit. Theother end of the tube 884 is connected to an outlet 886 of aconventional 500 cc nebulizer 887. The nebulizer 887 is provided with aninlet 888 which is connected to an entrainment gate 889 that is mountedon the inlet 888. The gate 889 is connected to across 892. The cross 892has an entrainment reservoir 893 mounted thereon as well as a volumeregulator 894. The cross is also connected to a large tube 896 formingthe expiratory side of the breathing circuit. The tube 896 is connectedto the outlet 897 of a failsafe pulse regulator 898 which has its inlet899 mounted on the outlet 819. The regulator 898 is provided with aservo port 901 which is connected into the venturi jet port 866 that isconnected to the venturi fitting 321. Nebulizer fittings 312 and 406 areconnected to the nebulizer port 902 and the auxiliary port 903respectively of the nebulizer 887.

The fail-safe pulse regulator 898 is provided with an exhalation port907 which is adapted to be closed by a diaphragm 907 pressurized fromthe servo port 901. The overpressure fail-safe relief valve 883 isprovided with an exhalation port 909 which is normally closed by adiaphragm 908 which is adapted to be moved to an open position by apredetermined pressure at the port 909 as, for example, a pressure of 10centimeters of H₂ O.

The volume regulator 894 is provided with an underfill valve 911 throughwhich ambient air can be entrained and is also provided with an overfillvalve 912 which will open to ambient in the event excess gas is beingsupplied to the reservoir 893.

A slit graded retard in the opening of the pulse regulator 898 can beprovided by installing an orifice (not shown) in the tubing connected tothe servo port 901.

Operation of the breathing circuit shown in FIG. 11 may now be brieflydescribed as follows for providing diffusion respiration. Auxiliary gasfor entrainment is delivered from the ventilator shown in FIG. 3 throughthe fitting 406 to the auxiliary port 903 provided on the nebulizer 887.Venturi servoing gas is supplied from the fitting 321 to the venturi jet866 of the exhalation valve assembly 872 into the servoing port 901 ofthe fail-safe pulse regulator 898. Nebulizer gas is delivered from thefitting 312 to the nebulizer port 902 of the nebulizer 887. Monitoringof patient airway pressures is provided by monitoring the gas at theport 821 and supplying the same to the fitting 369.

During the time that there is a dynamic flow of gas from the venturi jet851, this flow of gas causes entrainment of additional gas from thelarge bore inspiratory tubing 884, from the nebulizer 887 and from theentrainment reservoir 893. If more gas is required than that which isavailable in the reservoir 893, additional ambient air is supplied fromthe volume regulator 894 through the underfill 911.

As soon as the inspiratory phase has been completed and the gases are nolonger being supplied to the venturi jet port 866, the exhalation valveassembly 872 moves to an open position and the first flow of expiratorygases will flow through the expiratory port 819 through the outlet 897and through the large tubing 896 into the reservoir 893. The failsafepulse regulator 8989 has an opening delay causing part of thephysiological expiratory flow to vent to ambient with the balance beingdelivered into the reservoir. Should be reservoir 893 become overfilled,gas is vented to ambient through the overfill valve 912 of the volumeregulator 894. Since there is a slight delay in opening of the pulseregulator 898, the exhalation gases are released to ambient and are thegases having the highest carbon dioxide concentration.

During the exhalation phase exhalation gases cannot regress through theventuri into the inspiratory tubing 884 because of the directional check889 downstream of the nebulizer 887. The entrainment isolation valve 889is located downstream of the nebulizer 887 to prevent rain out ofaerosol secondary to an upstream location.

During operation of the ventilator, a constant flow of aerosol isgenerated by the nebulizer/humidifier 887 which is supplied through thelarge tube 884 to the entrainment port 848 of the exhalation valveassembly 872. Flow through the nebulizer is increased by theintroduction of gas through the auxiliary port 903. This fresh gas whichis supplied through the tube 884 is the first gas which is entrained bygases leaving the venturi jet 851. The slower the oscillation drain byvolumetric ventilation, the longer the expiratory phase and the greaterthe washout of the inspiratory circuit through the open orifice 907 ofthe pulse regulator 898 which is in very close proximity to the proximalairway of the patient. Therefore the first gas into the lung of thepatient has the lowest carbon dioxide. As the oscillatory rates increaseas during diffusion respiration, the flow around the breathing circuitincreases with the associated increase in minute volumes. Because of thehigher oscillatory rates and delay in opening of the pulse regulator898, the majority of ambient flow occurs through the overfill valve 912of the volume regulator 894.

The partial rebreathing circuit provided in the breathing circuit shownin FIG. 11 makes it possible to conserve breathing gases but at the sametime allows control over hyperventilation, and gives betterhumidification of inspired gases and less temperature drop with thebreathing circuit.

In the event that the expiratory circuit is overwhelmed by a massiveearly high pressure expiratory flow, the overpressure fail-safe reliefvalve 883 may purge a small initial volume of expiratory gases toambient through the port 909 by causing opening of the diaphragm 908until the pressure drops below 10 centimeters of H₂ O. The overpressurefail-safe relief valve 883 prevents an overpressure as, for example,those above 10 centimeters of water in the inspiratory circuit.

During many diffusive ventilatory procedures, the patient will breathespontaneously through a low level oscillatory CPAP. This is provided forby the rebreathing circuit shown in FIG. 11. During spontaneousinspiration entrainment is accelerated as proximal airway pressures risecausing less entrainment with flow of gas through the expiratory circuitbeing increased. Outlet flow to ambient is predominantly through theoverfill valve 912 of the volume regulator 894.

During spontaneous demand by the patient, venturi flow is acceleratedwith entrainment of additional gases peaking with the demand of thepatient. During expiration, the pulse regulator 898 clutches the flow toambient breathing creating a CPAP since wave. The failsafe pulseregulator 898 serves to vent the proximal airway to ambient with minimalmechanical dead space in the event of total mechanical ventilatorfailure permitting the patient to breathe spontaneously with littleeffort. If an occasion arises in which it is desired to wean the patientfrom the ventilator, the ventilator can be turned off while maintainingan aerosol delivery while the patient breathes essentially ambient air.

In the event there is any disconnect of any of the tubing in theventilator, the breathing circuit in FIG. 11 still permits spontaneousbreathing of the patient through the fail-safe pulse regulator orifice907. A disconnect of the nebulizer and/or auxiliary tubing will causeentrainment of ambient air through the ambient access valve 912 of thevolume regulator 894. An obstruction in the inspiratory tubing willreduce tidal volume by eliminating entrainment. However, in such event,the cap on the nebulizer may blow off or a large bore tubing will blowoff to release trapped nebulizer and auxiliary flow of gases. An alarmwill sound with a sustained rise in auxiliary gas pressure. A totalobstruction in the expiratory tubing will only serve to reduce theoxygen concentration and slightly increase expiratory resistance. Thisresult occurs because of entrainment of gas from ambient through thevalve 894 of the volume regulator and the total exhalation of theexhalation gases through the orifice 907 of the fail-safe pulseregulator 898.

In FIGS. 12 and 13, there is shown a quick disconnect assembly which isparticularly adapted for use in the ventilators hereinbefore described.As shown, such a quick disconnect assembly 916 consists of a femalefitting 917 and a male fitting 918. The female fitting consists of abody 921. The body 921 is provided with a threaded cylindrical extension922 which can be threaded into a panel or body to which gas is beingsupplied. The extension is provided with a bore 923 which opens into acylindrical socket 924 in the body 921 and that is open at the other endof the body. The body 921 is provided with a plurality of flats 926which are spaced circumferentially and are adapted to be engaged by asuitable wrench for screwing the fitting 917 into the body into which itis mounted. The body 921 is provided with an annular recess 927 adjacentthe forward extremity of the same and carries a retainer 928. Theretainer 928 is cylindrical in form and is provided with an inwardlyextending annular flange 929 which is adapted to seat in the recess 927.The other extremity of the retainer is provided with an inwardlyextending annular shoulder 931. The retainer 932 is provided with aplurality of axially extending slots 932 which are spacedcircumferentially around the retainer to provide segmental lips on theclamping end of the retainer.

The male fitting 918 consists of a body 936 which is provided with acylindrical hose extension 937 that is provided with spaced annular ribs938. The extension 937 is adapted to receive the end of a tubular hosewhich frictionally engages the ribs 938. The body 936 is provided with aradially extending flange 941 and a forwardly extending straight bayonet942. The body 936 is provided with a flow passage 943 which extendsthrough the extension 937 and through the bayonet 942. The bayonet 942is provided with a chamfer 944 on its outer extremity. The bayonet 942is provided with an annular recess 946 which carries an O-ring 947. Thebayonet 942 is also provided with an annular shoulder 948 which isprovided with a tapered ramping surface 949. An annular recess 951 isformed between the shoulder 948 and the flange 941.

Operation of the quick disconnect assembly 916 may now be brieflydescribed as follows. Let it be assumed that the female and male fitting917 and 917 are separated and it is desired to connect the same. Let itbe assumed that the female fitting 917 has been mounted in a body whichis in a fixed position. The male fitting can then be inserted into thesocket 924 by advancing the bayonet 942 forwardly into the retainer andso that the bayonet 942 enters the socket 924. As this occurs, theO-ring 947 will engage the wall of the socket 924 to form an airtightfit. As the advance of the male fitting into the female fittingcontinues, the inclined surface 949 on the shoulder 948 engages therounded shoulder 931 provided on the retainer to circumferentiallyexpand or cam outwardly the segmental lips so that the annular shoulder948 can enter the retainer 928. As soon as the shoulder 931 clears theshoulder 948, the shoulder 931 will snap behind the shoulder 948 to seatwithin the annular recess 951 to thereby retain the male fitting 918within the female fitting 917.

In the event it is desired to separate the male fitting from the femalefitting, it is only necessary to apply a pulling force to the malefitting 918 which will engage the shoulders to cause the shoulders toexpand outwardly the segmental lips of the retainer and to permit thebayonet 942 to be withdrawn from the socket 924.

When the male fitting 918 is mounted in the female fitting 917, theassembly is such that the male fitting 918 can rotate within the femalefitting 917. The retainer 928 prevents a piston effect rejection of thebayonet during pressurization. Use of the retainer with the clampingretainer which is slotted to provide segmental lips provides adequateretention capabilities while at the same time facilitating the insertionand removal of the male fitting 918 from the female fitting 917. By wayof example one design of the quick disconnect fitting assemblyaccommodated, a static pull release of eight pounds. Under dynamicconditions with 50 pound piston effect, five pounds was the averagerelease force.

The quick disconnect fitting assembly 916 as shown in FIGS. 12 and 13can be utilized for interior and exterior fittings. Even though theassembly 916 has quick disconnect capabilities it can withstand highfrequency use without showing wear.

Another embodiment of a quick disconnect assembly is shown in FIGS. 14and 15. The disconnect assembly 956 shown therein is very similar to thedisconnect assembly 916 shown in FIGS. 12 and 13. It consists of afemale fitting or socket 957 and a male fitting or bayonet 958 and aretainer 959. Most portions of the quick disconnect assembly 956 arevery similar to the corresponding portions in the previous embodimentwith certain changes. Thus, the female fitting or socket 957 is providedwith an annular surface 961 which extends substantially at right anglesto the longitudinal axis of the quick disconnect assembly. Similarly,the male fitting or bayonet 958 is provided with a surface 962 whichalso extends substantially at right angles to the longitudinal axis ofthe quick disconnect assembly. The retainer 959 is provided with theannular flange 921 and an annular shoulder 931 as was the retainer 928.However in place of the narrowly generally U-shaped slots 932 providedin the retainer 928 V-shaped slots 963 are provided in the retainer 959.These V-shaped slots 963 extend longitudinally of the retainer and openthrough one end of the retainer carrying the inwardly extending annularflange 929 to provide a plurality of longitudinally extending flexiblefingers 964. In the quick disconnect assembly 956, the retainer 951 iscarried by the male fitting 958 and the female fitting 957 is providedwith an annular camming surface 966 so that the flanged fingers 964 willengage the flange 966 and be cammed outwardly until they clear theforward extremity of the body 921 and drop into the recess 927 to latchthe female and male fittings into a unitary assembly.

It has been found that by changing the conformation of the quickdisconnect assembly as shown in the present embodiment with respect tothe embodiment shown in FIGS. 12 and 13 and by utilizing variousmaterials, the releasing force can be relatively preciselypredetermined. Thus it has been found that by providing the V-shapedslots 963 in place of the U-shaped narrow slots 932, greater flexibilityis provided in the fingers 964 to thereby lower the releasing force forthe quick disconnect assembly. In addition it has been found that byproviding the V-shaped slots, the number of times in which theassemblies can be connected and disconnected can be greatly increasedbefore there is a possibility of failure. Thus it has been found that byusing the V-shaped slots, connections and disconnections in excess of5,000 repeat operations can be performed without any danger of failure.In addition the pull apart force can still be retained at desired valueseven with the more flexible fingers by providing sharper angled surfacesas for example, the right angle surface engaged by the retainer 959 inthe embodiment shown in FIGS. 14 and 15.

In determining the number of operations which can be readily assimilatedby the quick disconnect assembly, the yield properties of the plasticsutilized must be taken into consideration. For example where it isdesired to provide a quick disconnect assembly which can withstandnumerous connections and disconnections as for example, in excess of5,000, materials shown as Nylon ST can be utilized for the bayonetwhereas as polyethysulfone can be utilized for the retainer. Thus it canbe seen that in constructing ventilators of the present inventionutilizing quick disconnect assemblies of the type hereinbefore describedthe type of disconnect assemblies can be selected for the particularapplication. For example, where the quick disconnect assemblies areutilized for external fittings provided on the ventilator where therewill be many repeated connect and disconnect operations during thelifetime of a ventilator, a quick disconnect assembly 15 of the typeshown in FIGS. 14 and 15 can be utilized with the materials hereindisclosed. On the other hand where the quick disconnect assemblies wouldbe infrequently disconnected and connected during the lifetime of theinstrument, the construction of the quick disconnect assembly shown inFIGS. 12 and 13 would be more appropriate.

It should be appreciated that the retainer 959 can be carried by eitherthe female or male fitting. Since typically in the present embodimentsof the quick disconnect assemblies the female fitting would be formed ofmetal and the male fitting of plastic, it generally would be preferableto have the retainer carried by the plastic male fitting rather than thelonger lasting metal female fitting. However if desired, the retainercan be carried by the female fitting and still operate in generally thesame manner.

The quick disconnect assemblies disclosed in the previous embodiments inaddition to having the quick disconnect and connect featureshereinbefore described also are immune to leaks. The O-rings 947provides a positive seal in the quick disconnect assembly to preventsuch leaks.

In FIGS. 16 through 21, there is disclosed a ventilator 971incorporating the present invention. As shown in FIG. 16, the ventilator971 is mounted upon a table 972 and is shown being utilized by a seatedpatient 973. The ventilator 971 consists of a console 974 which isconnected to a breathing circuit 976. The console 974 consists of a case977 which is formed of a suitable durable plastic such as Lexan. Thecase 977 is formed from a front bezel 978. The case also includes spacedparallel side walls 979 and 981, spaced parallel top and bottom walls982 and 983 and a rear wall 984, all of which may be injection moldedparts ultrasonically bonded together to form the case.

The bezel 978 is provided with an inwardly extending flange 986 which isdisposed rearwardly from the front surface. Screws 985 are utilized forsecuring the bezel 978 to the sidewalls 979 and 981 of the case 977. Theconsole 974 includes a front panel 987 that is secured to the flange 986by suitable means such as screws 988. As can be seen from FIGS. 16 and17, the front panel 987 is mounted on the left hand side of the bezel978. The console 974 also includes a door 989 which is secured by ahinge 991 to a vertically extending strip 992. The strip 992 is securedto the flange 986 by screws 993. The door is provided with a knob 994which is provided for rotating a latch member 996 carried by the doorand adapted to engage the front panel 987 to hold the door in a closedposition. The door when closed, encloses a compartment 997 in which thebreathing circuit 976 can be stored when it is not in use.

U-shaped lips 998 and 999 are secured to the top and bottom wallsrespectively. The outside surface of the bottom U-shaped lip 999 isgenerally flush with the exterior surfaces of the side walls 979 and 981and the rear wall 984 of the case 997 whereas the outside surface of thetop of the U-shaped lip 998 is recessed from the same outer surfaces insuch a manner so that one case can be stacked one above the other withthe U-shaped lip 999 on the bottom of a case above nesting outside ofthe U-shaped lip 998 provided on the top of the case below.

A U-shaped handle 1001 is provided as a part of the case 977 and issecured to the side walls 979 and 981 of the case. The U-shaped handle1001 has a size such and is rotatably mounted so that it can be swung360° around the case. This makes it possible for the handle to assumevarious positions as hereinafter described. Suitable means is providedfor securing the U-shaped handle 1001 to the side walls so that thehandle can be rotated about the case. Such means consists of a serratedbushing 1002 which has serrations provided on one surface which areadapted to engage the plastic of the side wall. The serrated bushing 102is provided with a threaded extension which extends through the sidewall and which is retained in engagement with the side wall by a nut 103threaded onto the threaded extension. A threaded shaft 104 is providedwhich extends through the end of the U-shaped handle 1001 and through anantifriction washer 1006 formed of a suitable material such as Nylatronand then through the bushing 1002 and is retained therein by a C-shapedclamp 1007.

A knob 1008 is secured to the other end of the threaded shaft 1004 andis provided for rotating the shaft. Since the shaft 1004 is threadedinto the bushing 1002 it can be seen that by rotating the shaft relativeto the bushing that the knob 108 can be used for clamping the ends ofthe U-shaped handle 1001 in the desired angular position. Thus as shownin FIGS. 16 and 17, the handle can be moved to a position that extendsdownwardly and slightly forwardly to cant the front panel in a slightlyupward direction when the console is resting on the table 972. Byloosening the knobs 1008 provided on the two sides of the case, it canbe seen that the handle 1001 can be moved to other desired positions asfor example, on top of the case to serve as a carrying handle or to therear where it is in an out-of-the-way position. Since the handle 1001can be rotated through 360°, the handle also can be utilized as abracket for supporting the instrument on a stand or on a wall or onother pieces of equipment.

As can be seen from FIG. 16, the outside surface of the door 989 carriesan illustration showing the manner in which the breathing circuitsshould be connected to use the ventilator. The front panel 987 carries aplurality of controls, sockets and the like as hereinafter described foroperation of the ventilator. It will be noted that these controls on thefront panel are recessed behind the front extremity of the bezel 978.This helps to insure that the controls provided on the front panelcannot be accidentally bumped to disturb their settings during the timethat the ventilator is in operation.

As hereinbefore explained the case 977 can be formed of a suitableplastic such as Lexan. Also, the case can be made in such a manner sothat it is substantially transparent so that the interior of the casecan be inspected without the necessity of removing the front panel. Thelexon plastic which is utilized in the case can be given a suitable tintto approve the appearance as for example, it can be given a bronze tint.If desired, a dividing panel (not shown) may be placed inside the caseto separate the storage compartment 999 from the compartment containingthe equipment associated with the front panel 987. The case 977 can beprovided with a plurality of knockouts if desired to make it possible toutilize the case for other types of ventilators as hereinafterdescribed. In addition, the case is provided with a plurality as forexample, two conical shaped recesses 1009 provided in the rear wall ofthe case which have recessed fittings mounted therein.

A schematic diagram of the pneumatic circuitry provided in theventilator 971 is shown in FIG. 18. As shown therein, the ventilator 971includes an inlet socket 1011 which is mounted in the upper rear recess(not shown) in the case. The inlet socket is connected to a conventionalfilter 1012. The inlet socket 1011 is adapted to be connected to aconventional source of air under pressure as for example, air having apressure of approximately 55 psi. The filter 1012 serves to removeforeign material from the air and also condenses the water vaportherein. The water condensed out of the air is supplied through apressure relief regulator 1014 to an outlet 1015. The pressure regulator1014 is set to open in the event of a pressure in excess of apredetermined pressure as for example, 50 psi to exhaust the air to theatmosphere to prevent an overpressure condition from occurring. Theoutlet port 1015 is mounted in the lower recess (not shown) and if thereis no water in the line as for example, in a hospital supply it can becapped. If there is water in the air as for example, in a homeapplication in which the ventilator is being supplied with air from asmall air compressor, a tube can be connected to the outlet 1015 anddrained into a container which can be emptied after use of theventilator.

The output from the filter 1012 is supplied through a pressure reductionregulator 1016. The pressure reduction regulator 1016 can be mounted onan inner wall of the case and is provided with a knob 1017 which isaccessible from the compartment 997 so that it can be adjusted to thedesired pressure, as for example, 40 psi. The gas under the reducedpressure from the regulator 1016 is supplied through a line 1018 to anadjustable orifice 1019 connected by a line 1021 to a manometer 1022.The manometer 1022 is typically mounted in the top wall 982 of the case977. The manometer gives a direct reading of the pressure in psi of thegas or air which is supplied from the pressure reducing regulator 1016.The adjustable orifice 1019 serves to reduce the fluctuations in the gason the manometer 1022 and serves to ensure that the manometer provides amean pressure reading.

The output from the pressure reducing regulator 1016 is also supplied toa nebulizer limiting orifice 1026 which can be of a suitable size suchas 0.040 of an inch. The orifice 1026 is connected to a socket 1027mounted on the front panel 987 and typically can be color coded yellow.The socket 1027 is connected to a flexible plastic line 1028 also colorcoded yellow which is connected to a nebulizer 1029 hereinafterdescribed in detail. As can be seen, a constant flow of gas is suppliedto the nebulizer 1029 from the socket 1027. This provides a constantaerosolization to the patient.

Gas from the output of the regulator 1016 is also supplied to a manualinspiration limiting orifice 1031 of a suitable size such as 0.024inches. The orifice 1031 is connected to a manually operated push button1032. The manual push button 1032 is spring loaded to a normally closedposition and can be moved manually to an open position against the forceof the spring therein.

When the manual push button 1032 is depressed, it supplies gas to asocket 1033 provided on the front panel. The socket 1033 is connected toa flexible plastic line 1034 color coded white. The line 1034 isconnected to a combination venturi jet and exhalation valve assembly1036 of the type hereinbefore described. Thus it can be seen that themanual push button 1032 provides an override which makes it possible tocause the ventilator to act as a resuscitation device.

Gas is also supplied from the pressure reduction regulator 1016 to theinlet 1037 of an oscillator cartridge 1038. As shown, the oscillatorcartridge 1038 is a normally open cartridge and is provided with a valvemember 1039 movable between open and closed positions by a diaphragm1041. When the cartridge 1038 is in its normally open position gas willflow from the inlet 1037 through an outlet port 1042 to a servo port1043 of a reset cartridge 1044. The application of gas to the inlet 1043causes pressure to be applied to a diaphragm 1046 which moves a valvemember 1047 from its normally open position to a closed position toocclude the flow of gas from an inlet port 1048 to an outlet port 1049.At the same time that the flow of gas from the oscillator cartridge 1038moves the reset cartridge 1044 from a normally open to a closed positiongas is also supplied to an initial flow obtunder 1051.

The flow obtunder 1051 is shown in detail in FIG. 19 and as showntherein consists of a cylindrical body 1052 which is provided with acylindrical extension 1053 that is adapted to have a hose or plasticline secured thereto. The body is provided with a cylindrical cavity orchamber 1054 which is in communication with a flow passage 1056extending through the extension 1053. The flow obtunder 1051 alsoincludes another body 1057 which is provided with a flange 1058 that isadapted to be ultrasonically bonded to the body 1052 to form an enclosedchamber or cavity 1054. The body 1057 is provided with an extension 1059which is adapted to be connected to a hose or line. The body 1057 isprovided with a cylindrical extension or protrusion 1061 which extendsinto the cavity or chamber 1054. A flow passage 1062 is formed in theextension 1059. Flow passages 1059 and 1062 are in communication withthe chamber 1054 and in communication with passages 1063 extendingdiametrically from the cylindrical extension and protrusion 1061. Asleeve 1064 formed of a suitable flexible material such as plastic isslidably mounted on the cylindrical extension or protrusion 1061 and isdisposed in an annular recess 1066 formed in the protrusion 1061 and isadapted to occlude the passages 1063. When gas is supplied to thepassage 1062, the gas comes into engagement with the sleeve 1064 andgradually expands the same so as to permit air to flow around the sleeveand out to the passage 1056. In this way it can be seen that there isprovided a gradual opening of the flow obtunder so that physiologicalstructures in the patient are not abruptly struck with a burst of gaswhile at the same time the flow obtunder does provide a good peak flowafter it has been gradually opened. Gas flowing from the flow obtunder1051 is supplied to the socket 1033 which is connected to thecombination venturi jet and exhalation valve assembly 1036.

Gas supplied from the outlet 1042 of the oscillator cartridge is alsosupplied through a check valve 1067 to the adjustable inlet 1068 of animpact metering cartridge 1069. The impact metering cartridge 1069 canbe adjusted to control the flow of gas and this gas is supplied to anoutlet 1071. The gas from the outlet 1071 is supplied to the inlet 1072of a frequency metering cartridge 1073. The rate of flow through thefrequency metering cartridge 1073 which also can be termed a ratemetering cartridge can be adjusted as shown. This adjusted flow rate ofgas is supplied through an outlet 1074 to the inlet 1048 of the resetcartridge 1044 which at this time is closed because of gas supplied tothe servo port 1043. Because gas cannot flow through the reset cartridge1044 there is a pressure build up and this gas under pressure issupplied to the servo port 1076 of the oscillator cartridge 1069 whichapplies pressure to the diaphragm 1041. The rate at which the diaphragm1041 of the oscillator cartridge moves the valve member 1039 from anopen to a closed position is determined by the rate of metered flow bythe frequency metering cartridge. As soon as there has been sufficientbuild up of pressure against the diaphragm 1041, the diaphragm 1041moves the valve member 1039 to a closed position to occlude the flow ofgas from the inlet 1037 to the outlet 1042. As soon as the valve member1039 oscillator cartridge 1038 is moved from an open to a closedposition the flow of gas through the combination venturi jet andexhalation valve assembly 1036 which also can be termed a "phasitron" isstopped. The remaining gas in the lines is dumped very rapidly throughthe phasitron 1036 which reduces the pressure behind the diaphragm 1046of the reset cartridge 1044 so that it rapidly moves from a closedposition to its normally open position. As soon as this occurs, the gaswhich is trapped behind the diaphragm 1041 of the oscillator cartridgeis bled out through the frequency metering valve or cartridge 1073through the inlet 1048 through the outlet 1049 which is connected to asocket 1077 mounted on the front panel 987 and which can becharacterized as a remote socket. The remote socket 1077 in certainapplications of the ventilator 971 can be vented to ambient andtherefore as soon as the gas pressure behind the diaphragm 1041 has beenreduced sufficiently, the diaphragm 1041 will move the valve member 1042to an open position to open the oscillator cartridge to again start thecycle hereinbefore described.

In certain applications of the ventilator 971 it may be desired tocontrol the frequency of oscillation of the ventilator remotely. This isaccomplished by connecting the remote socket 1077 by a line 1078 withboth the socket and the line 1078 being color coded in an appropriatecolor, as for example, green. The line 1078 is connected to an inletfitting 1080 of a manually operated push button assembly 1079 mounted onthe tee 1141. Operation of the push button assembly 1079 by the uservents the line 1078 to ambient.

Means is provided for controlling the pressure of the gases in theairway of the patient and consists of an impact knob 1081 and having theletter "A" thereon. The knob 1081 is mounted on the front panel 987 andis used for adjusting the impact metering valve 1069. Similarly, a knob1082 having the letter "B" thereon is provided on the front panel 987.It is used for adjusting the frequency metering valve 1073. The impactknob 1081 determines the inspiratory time and the frequency knob 1082determines the expiratory time. The inspiratory time is the time thatthe oscillator cartridge 1038 is open and the expiratory time is thetime that the oscillator cartridge 1038 is closed. As the impactmetering knob 1081 is turned towards a closed position, the slower therate of flow of gas through the same and the longer the oscillatorcartridge 1069 will remain open or in the inspiratory phase to therebylengthen the inspiratory time. The slower the rate of flow through theimpact metering valve 1069, the longer it will take to load thediaphragm 1046 of the reset cartridge 1044 and thus the longer it willtake the timing circuit to fill up. Conversely, the more that the knob1081 is moved to an open position, the shorter the inspiratory time orthe impact pulse to the patient.

With respect tot he frequency knob 1082, the position of this knobdetermines the length of time that the oscillator cartridge 1069 willremain in a closed position. It therefore determines how much gas willflow out of the lung of the patient before the next inspiratory flow isstarted into the lung. Thus it can be seen that by adjustment of theknobs 1081 and 1082, an IE or inspiratory expiratory time ratio can beestablished.

Means is provided for monitoring the pressure of gases in the airway ofthe patient and consists of a line 1086 which is connected to the outletof the phasitron 1036. The line 1086 is connected to a gauge socket1087. The socket 1087 is connected to an orifice 1088 and the orifice1088 is connected to a manometer 1089 mounted in the front panel 987which gives a reading of the proximal airway pressure. The orifice 1088serves to snub out pressure variations so that the manometer provides amean reading of the patient's proximal airway pressure. The line 1086and the socket 1087 also can be color coded in an appropriate color, asfor example, red. As can be seen from FIG. 16, the proximal airwaypressure is measured immediately behind the fitting 1091 which issecured to the phasitron 1036. The fitting 1091 is adapted to beconnected to a patient adapter (not shown).

The nebulizer which is used in conjunction with the present ventilator971 is shown in more detail in FIGS. 20 and 21. As shown therein itconsists of a cup-like member 1096 which is provided with a cylindricalsidewall 1097 and a dished bottom wall 1098. The cup-like member 1096 isformed with a depending rim 1099 which is provided with a lower planarsurface 1101 which is adapted to rest upon a flat surface to facilitatefilling of the cup-like member 1096. The rim 1099 is provided with acutout 1102 through which the yellow line 1028 can extend and isconnected to an elbow 1103. The elbow 1103 is bonded by suitable meanssuch as ultrasonic welding to a protrusion 1006 formed integral withbottom wall 1098. A central hollow post 1107 formed integral with thedished bottom wall 1098 extends vertically upward from the dished bottomwall 1098. A flow passage 1108 is provided in the protrusion 1106 andthe post 1107. The top o the post 1107 is provided with a small orifice1109 which is communication with the passage 1108. The top of the post1107 is provided with a convex surface 1111.

The cup-like member 1096 is provided with an enlarged cylindricalportion 1112 adjacent to the dished bottom wall 1098 which is provided.A sleeve 1114 is mounted over the post 1107 and is ultrasonically bondedonto the cylindrical portion 1112. The sleeve has an inner cylindricalpassage 1116 which is of greater diameter than the outer diameter of thepost 1107 and is in communication with a plurality of passages 1113, asfor example, four which are circumferentially spaced 90° apart aroundthe raised portion of 1112. The sleeve 1114 is provided with an upperwall 1117 which extends across the cylindrical passage 1116 in aposition slightly above the top of the post 1107. The wall 1117 isprovided with a dished recess 1118 concave in form in communication witha venturi-like flow passage 1119 in vertical alignment with orifice 1109and which is of a slightly greater diameter than the orifice 1109. Byway of example, the orifice 1109 can have a diameter such as 0.030whereas the orifice or passage 1119 can have a diameter such as 0.050.The sleeve 1114 is provided with cutouts 1121 on opposite sides abovethe wall 1117. The sleeve is also provided with another top wall 1122which has a bore 1123 therein. The bore 1123 is adapted to receive adiffractor plug 1124. The lower extremity of the diffractor plug isprovided with a convex surface 1126 which overlies the orifice 1119. Theupper extremity is in the form of a knurled cap 1127 to facilitateplacement and removal of the plug 1124.

The nebulizer 1029 also includes a quick disconnect cap 1131 which isadapted to be secured to the top of the cup-like member 1096. Thecup-like member 1096 is provided with outwardly extending segmented lips1132. The upper extremity of the cup-like member 1096 is provided withan annular recess 1133 with is adapted to receive an O-ring 1134 formedof a suitable material such as Silastic. The cap 1131 is provided withsegmented U-shaped portions 1136 which are adapted to frictionallyengage the segmented lips 1132 provided on the cup-like member 1096 sothat the cap can be cammed down on top of the O-ring 1134 to form aliquid-tight seal.

The cap 1131 is provided with a cylindrical depending extension 1138which is disposed over the top of the sleeve 1114 as shown in FIG. 20.The cylindrical extension 1138 is provided with a flow passage 1139which opens into a tee 1141 formed integral with the cap. In one leg1142 of the tee 1141, a flapper valve 1143 is provided which normallyrests against a spider-like retainer 1144 which ensures that the flappervalve can only open in an inward direction. The other leg 1146 of thetee 1141 is adapted to be connected to the inlet port of the phasitron1036. As can be seen, a manually operated push button valve 1079 issecured to the lower portion of the leg 1146 and opens into the tee.When the push button 1079 is operated, the line 1078 connected to theinlet 1080 is vented into the interior of the leg 1146.

With the construction shown, it can be seen that the gases which exitfrom the sleeve 1114 are introduced upwardly into the flow passage 1139provided in the cylindrical extension 1138 and will exit into the tee1141 where they will be carried into the phasitron 1036. As hereinbeforedescribed, the phasitron is a device which provides a negative ambientpressure at the outlet from the tee 1141 so as to enhance the travel ofthe humidified gases from the nebulizer 1096 to the airway of thepatient. The cylindrical extension 1138 depending down into the cup-likemember 1096 serves as an anti-spill device. For example, with thepresent nebulizer, it is be possible to have as much as 20 ccs of liquidin the nebulizer without spilling it in the event that the nebulizer istipped.

The outlet from the combination venturi jet and exhalation valveassembly 1036 is connected to a hose 1148 which is provided withstraight corrugations. The hose 1148 is a suitable length, as forexample, 18 to 24 inches and serves to collect water which may becontained within the exhaled gases passing through the exhalationoutlet. It has been found that the corrugations in such a length of hoseare adequate to retain any moisture which may precipitate out of theexhaled gases during a treatment. After the treatment, the hose can beremoved and stretched and cleaned to remove the water therefrom so itcan be ready for the next use. In this way, water is prevented fromdripping onto the patient during use of the ventilator.

In operation of the nebulizer 1029 shown in FIGS. 20 and 21, a constantflow of source gases is supplied to the nebulizer at a pressure of, forexample, 40 psi which in the nebulizer fractionates the liquid intoparticles having a means average size of approximately six microns.Typically a nebulizer of this size can put out approximately 120milliliters an hour. It can be seen that when gas is introduced into theelbow 1103 and passes through the orifice 1109 that any liquid withinthe cup-shaped member 1096 will be drawn up by a capillary attractionthrough the passage 1113 through the passage 1116 and then be introducedwith the air through the orifice 1119 against the diffractor 1129. Thediffractor causes the liquid entrained in the air to be broken up intovery small droplets and to be discharged through the cutouts 1121 in thesleeve 1114. By providing a plurality of passages 1113 at differentangular positions and by providing the concave or dish-shaped bottomwall 1098 for the cup-like member 1096, the nebulizer can be held invarious orientations and still remain operative. The large surface areasprovided by the outer surface of the center post 1107 and the innersurface of the sleeve 1114 facilitate adhesion of the liquid as it isdrawn up by capillary attraction in the nebulizer. The orifice orpassage 1119 serves in effect as a throat of a venturi to cause apressure drip across the top of the post 1107 to facilitate movement ofliquid by capillary attraction. It is also believed that this particularnebulizer particularly efficacious in causing the water particles to becharged with positive ions which inhibits coalescing of the waterparticles into a liquid before the water particles enter the patientairway.

Also in operation of the nebulizer 1029, the flapper valve 1143 isoperated inwardly as soon as a pressure differential of approximately 1to 2 centimeters of water occurs which allows additional ambient air tobe entrained into the phasitron and delivered to the patient's airway.When humidified gases are delivered from the nebulizer 1029 to thephasitron or combination venturi jet and exhalation valve assembly 1036,the gases will overwhelm the orifice and the servo diaphragm 861 willcause the venturi body 826 of the combination venturi jet and exhalationvalve assembly 1036 to move forward to close the exhalation valve. Thegases introduced into the venturi jet assembly 1038 create a subambientcondition which causes the flapper valve 1143 to open additional ambientair entrained. The ambient air moves across the top of the outlet of thenebulizer creating an additional vacuum and causing additionalhumidified gases to be delivered into the airway of the patient. Theremainder of the operation of the combination venturi jet and exhalationvalve assembly 1036 is in the manner hereinbefore described.

Another embodiment of a ventilator incorporating eh present invention isshown in FIGS. 22 through 23. The ventilator 1151 shown therein ismounted upon a floor stand 1152. The floor stand 1152 consists of a fivelegged pedestal 1153 which is provided with locking casters 1154. Acenter post 1156 is mounted in the pedestal 1153. A bracket 1157 ismounted on top of the center post 1156 and engages the U-shaped handle1011 carried by the case 977. Another bracket 1158 is secured to the arm1011 and has clamped thereto an arm assembly 1159. The arm assembly 1159includes a L-shaped arm 1161 and a telescoping L-shaped arm 1162 whichtelescopes into the arm 1161 through a coupling 1163. A flexibleextension 1164 is carried by the end of the arm 1162 and carries abreathing head assembly 1166. A ring 1167 is secured to the bracket 1158and carries a nebulizer 1029 of the type hereinbefore described. [A line1168 is provided which is connected to the rear of the case of theventilator and is adapted to be connected to a suitable source of gasunder pressure as for example a source of gas under pressure in ahospital.]

A schematic diagram of the ventilator shown in FIG. 22 is shown in FIG.23. As shown in FIG. 23, the pneumatic circuitry is very similar to thatutilized in connection with the ventilator 971 hereinbefore described inconjunction with FIGS. 16 through 21.

All of the elements in FIG. 23 which correspond to those in FIG. 18 havebeen designated with the same identifying numerals. The additionalcomponents provided in FIG. 23 include a master on/off switch 1171 whichis provided with a control knob 1172 accessible from a front panel 1173mounted on the case 977. The two control knobs 1081 and 1082 provided inthe previous embodiment have been moved up on the control panel so thatall of the three knobs 1081, 1082 and 1172 are in vertical alignment.The manual on/off switch 1171 turns the ventilator on and off from thefront panel when the ventilator is connected to a supply of gas.

Ventilator 1151 also includes a constant positive airway pressurecartridge 1174 which has an inlet 1176 that is connected to the outletof the pressure adjusting regulator 1016. The cartridge 1174 is alsoprovided with a servo port 1177 which is connected by a line 1086 to thecombination venturi jet and exhalation valve assembly 1036 to sense thepatient airway pressure. The cartridge 1174 is also provided with anoutlet 1178 which is connected to the socket 1033. An adjustablemetering valve 1181 is placed in pneumatic circuitry just ahead of theflow obtunder 1051. The adjustable metering valve 1181 is provided witha knob 1182 which is accessible from the front panel 1173 andimmediately below the meter 1089.

It should be appreciated that although in the schematic diagram shown inFIG. 23 that both the adjustable metering valve 1181 and the flow ofobtunder 1051 have been provided in series in the same circuit, that thetypical application would utilize either one or the other because thetwo in series would provide too great a pressure drop. Thus in oneembodiment of this ventilator, the flow obtunder 1051 would be usedwithout the adjustable metering valve 1181 and conversely in anotherembodiment the adjustable metering valve 1181 would be used in place ofthe flow obtunder 1051.

The ventilator 1151 also includes an additional check valve 1183 whichis placed in series with the servo port 1043 of the reset cartridge 1044and a fixed orifice 1184 of a suitable size such as 0.018 inches and inseries with either the adjustable metering valve 1181 or the initialflow obtunder 1051 depending which is present. The orifice 1184 serves atiming circuit dump orifice. In a typical ventilator only one of two,the metering valve 1081 or the flow obtunder 1051 would be used.

The sockets 1027, 1077, 1033 and 1087 provided on the front panel 1173are shifted from below the manometer 1089 as shown in FIG. 17 to theright hand side of the panel 1173 and are arranged in the same orderfrom the top to the bottom. In addition, the pushbutton 1032 has alsobeen moved to the upper right hand side of the panel 1173 so it ispositioned above the sockets hereinbefore described.

The breathing circuit 1193 shown in FIG. 22 is provided as a part of theventilator 1151 and consists of the nebulizer 1029 which is connected toa tee assembly 1194. The tee assembly is connected to a rebreathing bag1196 of the type hereinbefore described. The tee is connected to abreathing tube 1197 which is connected to a combination venturi jet andexhalation valve assembly 1036. Another breathing tube 1198 is alsoconnected to the exhaust side of the combination assembly 1036 and isconnected into the tee assembly 1194 which is connected to therebreathing bag 1196. A water trap 11999 is connected into the breathingtube 1198 and is used for collecting water which precipitates out of theexhaled gases.

An illustration 1184 is provided on the outside of the door 989 toindicate to the user how the ventilator is to be connected.

The operation of the ventilator shown in FIG. 23 is very similar to thatdescribed in conjunction with the ventilator shown in FIGS. 16 through21. The ventilator is turned on and off by the use of the knob 1172 ofthe master on/off switch 1171. When it is turned on, gas flows in themanner hereinbefore with the previous embodiment. Gas is suppliedthrough the line 1034 to the combination venturi jet and exhalationvalve assembly or phasitron 1036 through the fitting 1091 into theairway of the patient. Humidified gases from the nebulizer 1029 are alsosupplied to the phasitron 1036. In the present embodiment of theventilator, the constant positive airway pressure cartridge 1174 isalways being supplied with the pressure of gases in to patient's airway.When the pressure in the airway drops below a predetermined value asdetermined by the setting on the cartridge 1174, additional source gasis supplied to the socket 1033 through the outlet 1178 of the cartridge1174.

Any pressure build up in the passages leading to the socket 1033normally would effect the operation of the reset cartridge 1044. Thishowever is prevented by the isolation check valve 1183 which isolatesthe reset cartridge 1044 from any pressure created by the CPAP cartridge1174. By providing this isolation check valve 1183 it is possible toprovide a constant positive airway pressure for the patient while at thesame time retaining cyclic operation of the ventilator. Thus with thepresent ventilator it is possible to provide a base constant positiveairway pressure to the patient while at the same time scheduling cyclingint he desired manner with the desired IE ratio by adjustment of theknobs 1081 and 1082.

The rate of inspiratory flow during the inspiratory phase can beadjusted by adjustment of the knob 1182 to increase or decrease the flowas desired while still retaining the capability of varying theinspiratory expiratory ratio in the desired manner. In this way it ispossible to take care of a great variety of patients. By cutting down onthe flow of gas by use of the adjustable metering valve 1181 it ispossible to gradually wean a patient from use of the ventilator. Greatvariations in timing can be obtained. For example oscillations varyingfrom 400 to 800 cycles per minute can be readily obtained. Because ofthese capabilities, the ventilator is particularly useful in treatingobstructive pulmonary disease as well as cardiovascular andcardiopulmonary diseases. It also can be utilized for weaning or foracute heart failure and a multitude of other therapeutic activities.

In FIG. 24 there is shown a wave form diagram showing the manner inwhich the ventilator 1151 operates. Thus, there is provided a wave form1186 which shows active or percussive phases 1187 and pause or restingphases 1188. Each percussive phase includes a plurality of inspiratorypeaks or phases and a plurality of expiratory phases or peaks with theinspiratory peaks being represented by the upwardly pointing peaks 1189and the expiratory peaks being represented by the downwardly extendingpeaks 1191. It will be noted that during the time these measurementswere being made that near the right hand end of the wave form 1186, theamplitude was increased substantially by adjustment of the knob 1182without increasing or decreasing the IE ratio or appreciably changingthe length of the inspiratory expiratory periods.

Still another embodiment of a ventilator incorporating the presentinvention is shown in FIGS. 25 through 31. The ventilator 1201 shown inFIG. 25 is in many respects similar to the ventilators hereinbeforedescribed. It includes a stand 1152 which has mounted thereon aventilator module 1202, an accessory module 1203 and a monitor module1204. All three of the modules are provided with a case 977 and a handle1011 of the type hereinbefore described. The cases 977 are provided withlips which can seat or nest within each other so that the modules can bestacked one above the other as shown in FIG. 25 and be supported on asingle stand 1152.

The schematic circuitry for the ventilator 1201 is shown in FIG. 26. Asshown therein, sockets 1206 and 1207 are provided on the rear of theaccessory module 1203. The socket 1206 is adapted to be connected to asuitable source of oxygen under pressure as for example approximately 50psi and similarly, the socket 1207 is adapted to be connected to asuitable source of air under pressure, as for example a source having anapproximate pressure of 50 psi. The sockets 1206 and 1207 are connectedto a conventional oxygen blender 1208 which is mounted in the accessorymodule 1203 and which is provided with a control knob 1209 accessiblefrom the front panel 1211 of the accessory module 1203. By adjustment ofthe knob 1209, the ratio of oxygen to air can be adjusted to suit theneeds of the patient.

The output of the blender 1208 is connected to an alarm light 1212 andan audible alarm 1213, both of which are mounted on the front panel 1211to give an alarm in the event that gas of inadequate pressure issupplied by the blender 1208.

Gas is supplied from the output of the blender 1208 to an operatingpressure regulator 1214. The output of the regulator 1214 is suppliedthrough an orifice 1019 of the type hereinbefore described to amanometer 1022 which measures the outlet pressure of the gas from theregulator 1214. The regulator 1214 is adjusted to provide the desiredoutput pressure, as for example approximately 40 to 50 psi for an adultand ranging from 20 to 30 psi for a neonate. The regulator 1214 serves adual function in that it stabilizes the inlet pressure to the patientand in addition it tailors the pressure to the size of the patient.

Gas from the regulator 1214 is supplied to an inlet 1216 of a demandconstant positive airway pressure regulator 1217 hereinafter calleddemand CPAP regulator. Gas from the regulator 1214 is also suppliedthrough a limiting orifice 1218 to a manual pushbutton valve 1219 on thefront panel 1223 to a manual pushbutton valve 1219 on the front panel1223 to the socket 1033. Socket 1033 is connected by line 1034 to acombination venturi jet and exhalation valve assembly or phasitron 1036.As pointed out with respect to the previous embodiments, the operationof the pushbutton 1219 overrides all of the other functions in theventilator and provides manual resuscitation for the patient.

Gas is also supplied from the regulator 1214 through a master on/offswitch 1221 which is provided with a control knob 1222 accessible on thefront panel 1223 of the ventilator module 1202. Gas in addition to beingsupplied to the master on/off switch 1221 is also supplied to anebulizer metering valve 1226 which is connected to the nebulizer socket1027 and which is connected by the line 1028 to a nebulizer 1225. Thenebulizer metering valve 1226 is provided in place of an adjustableorifice provided in the previous embodiments of this invention and has aknob 1227 on the front panel 1223.

From the foregoing pneumatic circuitry, it can be seen that a number ofthe components of the ventilator bypass the master on/off switch 1221which makes certain functions obligatory as soon as source gas isconnected to the ventilator. Thus, the demand CPAP regulator 1217, themanual inspiration valve 1219, as well as the nebulization providedthrough the nebulization metering valve 1226 bypass the master on/offswitch 1221. In addition, the failsafe alarm system 1228 bypasses theswitch 1221.

Gas is delivered from the outlet of the manual inspiratory valve 1219 tothe inlet 1229 of a normally closed failsafe sensitivity cartridge 1231.Gas is also delivered to one side of the one-way check valve 1232. Sincegas cannot flow through the check valve 1232, gas pressure will build upand enter the means pressure rise calibration valve 1233 which isadjusted internally to provide a predetermined rate of flow of gas intoa mean pressurized reservoir 1236. This rate of flow can be adjusted toany suitable predetermined value, as for example, one which will cause asufficient pressure rise within one to two seconds to move the diaphragm1237 of the failsafe sensitivity cartridge 1231 to move the valve member1238 to an open position. This permits gas to flow from the inlet 1229of the cartridge 1231 through a failsafe loading check valve 1239 to aservo port 1241 of a failsafe cartridge 1242. The gas pressurizes thediaphragm 1233 to move the valve member 1244 to an open position. Thislocks the failsafe cartridge 1231 in the open position so that gassupplied through the manual inspiration valve 1219 is supplied to aninlet 1246 through an outlet 1247 which is connected to a failsafegovernor alert 1248 and also to a visual alert 1249.

It can be seen that this failsafe circuitry prevents an overpressurefrom being applied to the patient airway either through the manualinspiration valve 1219 or through the demand CPAP regulator 1217. Thefailsafe alarm circuit 1228 remains in a locked out position until thegas behind the diaphragm 1243 of the failsafe cartridge 1242 is relievedas for example via the alert reset manually operated pushbutton 1251. Assoon as this occurs, the failsafe cartridge 1242 returns to its normallyclosed position. In addition to the adjustment provided on thecalibration valve 1233, the failsafe cartridge is provided with a knob1252 on the front panel 1223 which can be utilized for adjusting thespring pressure applied to the diaphragm 1237 to thereby adjust theopening and closing pressure for the valve member 1238 operated by thediaphragm 1237. The failsafe governor alert 1248 acts as a purge for thegases supplied to it in addition to reacting as an audible alarm. Fromthe foregoing description it can be seen that the failsafe alarm circuit1228 is always effective even though the master on/off switch 1221 isnot turned on.

When the master on/off switch 121 is in the off position, gas issupplied from the regulator 1214 through an outlet port 1256 of themaster on/off switch 121 which can be called the autophase pot and issupplied to an autophase isolation check valve 1257 and then the gas issupplied to a phasing segment 1258 of a conventional ventilationcircuit. This circuit supplies gas to a servo port 1259 to actuate adiaphragm 1261 to move a valve member 1262 from its normally openposition to a closed position of an inspiratory cartridge 1263. Thus itcan be seen that the inspiratory cartridge 1263 is moved to a closedposition by the auto phase circuit of the master on/off switch 1221 atthe time source gas is connected to the ventilator 1201 prior to themaster on/off switch being turned on to prevent a sudden rush ofinspiratory air gas to the airway of the patient represented by theschematic pulmonary structure 1264 through the inspiratory cartridge1263. Thus it can be seen that before the master on/off switch 1221 isturned on demand CPAP is functioning, the manual override is functioningand the nebulization apparatus is functioning. In addition, the failsafesystems are functioning and the autophase system is functioning. Withthe master on/off switch turned off, the ventilator serves as anexcellent weaning system. In addition, the CPAP cartridge which is inoperation provides excellent ventilation to a patient if the patient hada left-sided heart failure to thereby provide effortless inspiratorybreath while at the same time providing a positive airway pressure. Inaddition, manual override is provided if it is needed.

The conventional ventilatory system which is a time cycled ventilatorand the diffusive high frequency ventilatory system can now bedescribed. The master on/off switch 1221 is turned on and gas issupplied from its outlet pot 1266 to the inlet 1267 of the inspiratorycartridge 1263. This inspiratory cartridge 1263 which can be called amonopulse cartridge or in other words a time cycled ventilator isnormally open but is closed because of operation of the autophasecircuit hereinbefore described when source gas pressure is applied tothe ventilator 1201.

Let it be assumed that the inspiratory cartridge 1263 opens in a mannerhereinafter described. When the cartridge 1263 opens, the valve member1262 will open to permit flow of gas from the inlet 1267 through theoutlet 1268. The gas is supplied to an inlet 1269 of a normally closedtransition delay cartridge 1271 and therefore the gas can flow nofurther. Gas from the outlet 1268 is also supplied through a rangecompensator orifice 1272 of a suitable size such as 0.013 inches. Therange compensation orifice 1292 bleeds into a perforated ambient mufflerin the form of tubing 1273 which is provided with a plurality of holesor perforations 1274 which slowly leak gas out of the system to ambient.This prevents a lockout of the system and ensures that the system willkeep on cycling.

Gas from the outlet 1268 is also supplied to the servo port 1276 of anormally open inspiratory reset cartridge 1277. Gas is supplied to adiaphragm 1278 which moves the valve member 1279 to a closed position.Gas is also supplied from the outlet 1268 of the inspiratory cartridge1263 through a base line isolation check valve 1281 to a servo port 1282of an interruption interval cartridge 1283. The application of gas tothe servo port 1282 acts upon the diaphragm 1284 to move the valvemember 1286 to a closed position. This servo port 1282 is connected to abase line pause needle valve 1287 which is provided with a knob 1288accessible on the front panel 1223. The needle valve 1287 is used tobleed the circuit which pressurized the diaphragm 1284. The base linepause needle valve 1287 is connected to the perforated ambient muffleror tubing 1273.

As hereinbefore described gas is supplied from the outlet 1268 of theinspiratory cartridge 1263 to the inlet port 1269 of the transitiondelay cartridge 1271. At the same time gas is supplied to the outlet ofa transition reset check valve 1289 to ensure that no gas can flowthrough the check valve 1289. Gas is also supplied to a transition delaytime needle valve 1291 which is adjustable internally of the case 977and supplies gas at a controlled rate to a diaphragm 1292. When asufficient pressure has been created against the diaphragm 1292, a valvemember 12293 is moved to an open position. Thus it can be seen that thetransition delay cartridge provides a delay. As soon as cartridge 1271opens, gas is supplied from the outlet 1268 of the inspiratory cartridge1263 to the inlet 1269 of the transition delay cartridge 1271 and gas issupplied to the outlet 1294. The gas then flows through an interruptioninterval pressure rise needle valve 1295 which is provided with a knob1296 (also knob E) accessible on the front panel 1223 through anisolation check valve 1297 and then to the socket 1033 which isconnected by a line 1034 to the combination venturi jet and exhalationvalve assembly or phasitron 1036. Thus inspiratory flow is supplied tothe patient at a rate controlled by the control knob 1296 of the needlevalve 1295 to control the inspiratory flow.

At the same time that the gas is being supplied from the outlet 1294 tothe interruption interval pressure rise needle valve assembly 1295, gasis also supplied from the outlet 11294 of the transition delay cartridge1271 through an isolation check valve 1298 to an inspiratory timemetering valve 1299 which is provided with a knob 1301 (also knob D)accessible from the front panel 1223 which is provided for regulatingthe inspiratory time. Gas flows from the inspiratory time metering valve1299 into a phasing segment 1302 of the pneumatic circuitry. Gas flowsfrom the phasing segment 1302 into the inspiratory reset needle valveassembly 1303 which is provided with a knob 1304 (also knob C)accessible on the front panel 1223.

Gas metered by the inspiratory reset needle valve assembly 1303 issupplied to the inlet 1306 of the inspiratory reset cartridge 1277.However, as explained before since a pressure is applied to thediaphragm 12278 the valve member 1279 is in a closed position andprevents the gas from being supplied from the inlet 1306 to the outlet1307 which is vented to ambient. Since gas cannot escape to ambientthrough the outlet 1307, gas which is metered through the needle valve1299 is supplied to the servo port 1259 of the inspiratory cartridge1263 and gradually builds up a pressure against the diaphragm 1261 andmoves the valve member 1262 after a predetermined pressure buildup asdetermined by the adjustment of the needle valve 1299 to a closedposition. As soon as the inspiratory cartridge 1263 is closed, gas nolonger is supplied from the outlet 1268 through the base line pauseoscillation check valve 1281 to the servo port 1282 of the interruptioninterval cartridge 1283. As soon as gas under pressure is no longerbeing delivered to the servo port 1282, gas behind the diaphragm 1284will be bled out through the base line pause needle valve 1287 throughthe perforated ambient muffler 1273 to ambient. At the same time the gasbehind the diaphragm 1278 of the inspiratory reset cartridge 1277 isbled down through the perforated ambient muffler 1283 to ambient. Assoon as the valve member 1279 of the inspiratory reset cartridge 1277opens, gas behind the diaphragm 1261 of the inspiratory cartridge 1263will be bled out through the needle valve 1303 and through the inlet1306 and the outlet 1307 of the inspiratory reset cartridge 1277 toambient. The valve member 1262 of the inspiratory cartridge 1263 thenmoves to its normally open position to start a new cycle.

This cyclic operation will continue at a rate determined by thepositioning of the knobs 1301 (knob D) and 1304 (knob C) to provide anoperation which is very similar to the operation of a time cycledconvection ventilator. A frequency up to approximately 40 cycles perminute can be obtained with this time cycled operation.

The operation of the high frequency diffusion ventilation portion of theventilator 1201 shown in FIG. 26 may now be described. Let it be assumedthat the master on/off switch 1221 is turned on. Gas is supplied fromthe outlet 1266 to the inlet 1311 of a normally open primary oscillatorcartridge 1312. Gas flows through the cartridge 1312 through an outlet1313 to the servo port 1314 of oscillator reset cartridge 1316. This gasforces the diaphragm 1317 to move a valve member 1318 to a closedposition. Gas also flows from the outlet 1313 into the servo port 1319of a normally open failsafe oscillator or counterpulse cartridge 1321.The gas operates upon a diaphragm 1322 to move a valve member 1323 to aclosed position. At the same time gas is also supplied from the outlet1313 to an adjustable frequency needle valve 1324 which is connected tothe counter pulse socket 1077 on the front panel 1223. The valve 1324 isprovided with a knob 1326 (also knob A) accessible on the front panel1223. If the knob 1326 is rotated to close needle valve 1324,oscillation will gradually decrease until it ceases. If the knob 1326 isrotated to open the needle valve 1324 gas will be drained more rapidlyinto the counterpulse socket 1077 and into line 1078 to cause a higherfrequency of oscillation. Gas is also supplied from the outlet 1313 ofthe primary oscillator cartridge 1312 to a servo port 1327 of a chopperfrequency counter 1328. Gas supplied to the port 1327 operates upon thediaphragm 1329 which carries an L-shaped chopper flag 1331 whichoscillates in accordance with the pressure pulses applied to thediaphragm 1329. The hopper flag 1329 forms a part of a conventionalinfrared frequency counter (not shown) which has an output display 1332on the panel 1223. The counter is provided with a push to start button1333 to display the frequency being measured. The counter is providedwith its own self contained battery.

Gas is also supplied from the primary oscillator cartridge 1312 throughits outlet 1313 to a timing circuit which includes a primary oscillatorisolation check valve 1337 and a normally open needle valve 1338. Meansis provided for adjusting the needle valve 1338 and consists of an Allenhead screw 1341 mounted on the front panel 1323 and identified as the Eof the I/E ratio. When valve 1338 is wide open, gas flows through itvery rapidly through the outlet 1339 into the phasing segment up to theinlet 1340 of the normally open oscillator reset cartridge 1316. Sincethe valve 1318 of cartridge 1316 is closed, the gas has no where to flowbut into the servo port 1342 of the primary oscillator cartridge 1312and acts upon the diaphragm 1343 to move the valve member 1344 to aclosed position. Movement of the valve member 1344 to the closedposition occurs very rapidly to shut off the flow of gas through theoutlet 1313 of the primary oscillator cartridge 1312.

In order to increase the time of close down of the primary oscillatorcartridge or in other words increase the inspiratory time, it is merelynecessary to adjust the needle valve 1338 on the front panel 1223 to amore closed position until the desired close down rate has beenachieved. This adjustment of the valve 1338 changes the I/E ratio. Thisneedle valve 1338 in effect provides a timing circuit for running of thecounterpulse which is supplied to the socket 1077. If it is desired toshorten the time of the counterpulse, the valve 1338 is moved toward theopen position.

The frequency rate of the counterpulse is controlled by the needle valve1324 which is provided with a control knob 1326 (knob A) on the frontpanel 1223. The more that the valve 1324 is opened up, the faster thegas is bled down from the servo port 1317 of the oscillator resetcartridge 1316.

The area behind the diaphragm 1317 of the oscillator reset cartridge1316 is bled down through a needle valve assembly 1348 which is providedwith an Allen head adjustment 1349 on the front panel. The adjustmentscrew 1349 is identified as the I of the I/E ratio. After flowingthrough the valve assembly 1348, gas flows to the counterpulsing socket1077 through the frequency valve 1324. By closing the valve assembly1348, the frequency can be decreased to a rate of approximately 700times a minute. By opening the needle valve 1348, the frequency can bereadily increased, for example, to a rate up to 1,500 times a minute.

In the description of the operation of the ventilator 1201 shown in FIG.26 thus far described, it can be seen that the frequency of thecounterpulses can be varied without varying the amplitude and that thecounterpulses are 180° out of phase from the pulses from the primaryoscillator cartridge 1312. The amplitude of the counterpulses can bevaried as hereinafter described.

When the master on/off switch 1222 is turned on, gas is supplied throughan oscillatory CPAP/PEEP valve 1351 which is provided with a controlknob 1352 (also knob B) on the front panel 1223. The needle valve 1351meters gas through the normally open interruption interval cartridge1283, then up through the normally open parallel oscillator cartridge1321 which is being opened and closed by the timing circuit hereinbeforedescribed 180° out of phase with or inverse to the opening and closingof the primary oscillator cartridge 1312. The opening and closing ofthis timing circuit will determine the flow through the paralleloscillator cartridge 1321 which determines the flow of gas through thesocket 1033 to the phasitron 1036. The amplitude or volume flow of thegases to the phasitron 1036 is controlled by the opening and closing ofthe needle valve 1351. The amplitude of the gases controlled by thevalve 1351 (by knob B) is separated from the frequency controlled by thecontrol knob 1326 (knob A). Thus it can be seen that there has beenprovided a timing circuit that provides a counterpulse or a subambientphase potential which also opens and closes the parallel oscillatorcartridge 1321 that controls the primary flow to the phasitron socket1033.

The interruption interval cartridge 1283 opens and closes every time thetime cycled parallel oscillator cartridge 1321 opens and closes. Everytime interruption interval cartridge 1283 closes gas cannot flow fromthe master on/off switch through the oscillatory CPAP/PEEP needle valve1351 which controls the flow to the parallel oscillator cartridge 1321.When this flow is stopped, the counterpulses hereinbefore described arestill provided to the swivel tee 1421 to provide diffusion. Thus thereis provided a small amount of flow to the patient coming through theswivel tee 1421. This gas flow is not being supplied from the main gasflow from the socket 1033 to the venturi jet of the phasitron 1036. Thusit can be seen that a controllable diffusive ventilation system has beenprovided in the present ventilator in addition to the conventionalconvection ventilation system hereinbefore described. In order toprovide this diffusive ventilation int eh ventilator, the principaladdition to the pneumatic circuitry, has been the parallel oscillatorcartridge 1321.

The demand CPAP regulator 1217 is provided with a diaphragm 1356 whichhas a fixed spring 1357 which urges the valve member 1358 carried by thediaphragm 1356 to an open position and an adjustable spring 1359 whichmoves the valve member 1358 towards a closed position. The force appliedto the adjustable spring 1359 is adjusted by a knob 1361. The demandCPAP regulator 1217 is provided with a servo port 1362 which isconnected to the proximal airway monitor 1089 and is connected to thegauge socket 1087 on the front panel 1223 that is connected to thecombination venturi jet and exhalation valve assembly 1036. Thecartridge 1217 is also provided with an outlet 1363 which is connectedto a CPAP isolation check valve 1364 that is connected to the phasitronsocket 1033 on the front panel 1223. Thus it can be seen that theregulator 1217 will supply gas under demand to the airway of the patientwhen the gas pressure in the proximal airway of the patient drops belowa predetermined value. The diaphragm 1356 of the cartridge 1217 alwayssees the proximal airway pressure. The adjustable spring 1359 can beadjusted by use of the knob 1361 to provide a predetermined airwaypressure, as for example, five centimeters of water pressure before thevalve member 1358 is moved to a closed position. Thus the cartridge 1217will only move to a closed position when five centimeters of pressure isestablished in the patient airway. If the proximal airway pressure isreduced below this valve, the cartridge 1217 will open and provide anaccelerating flow of gas. Thus for example, the patient by suction couldcause the pressure to drop in the pressure airway to cause the operationof the demand CPAP cartridge 1217 thereby giving it its name. Asexplained previously, the demand output from the CPAP regulator 1217 issupplied through the isolation check valve 1364 to the phasitron socket1033 which is connected to the combination venturi jet and exhalationvalve assembly 1036. The demand CPAP regulator 1217 acting inconjunction with the combination venturi jet and exhalation valveassembly 1036 works well because the combination venturi jet andexhalation valve assembly 1036 acts as a pressure dampening governor.

Now let it be assumed that there has been an airway disconnect betweenthe ventilator 1201 and the patient. As soon as this occurs, the demandCPAP regulator 1217 will sense this occurrence and will open to supplygas to the phasitron socket 1033. As the flow of the gas accelerates,there will be a pressure build up in the lines supplied to connect tothe socket 1033 which are connected through the normally open failsafecartridge 1242 to the audible and visual alarms 1248 and 1249.

In order to prevent an overpressure condition from occurring, anaccessory pressure limiting regulator 1366 has been provided which isconnected to the phasitron socket 1033. By way of example, thisregulator 1366 can be adjusted to a suitable pressure as for example, apressure of 16 psi which translates to approximately 90 centimeters ofwater pressure. When this pressure is reached, the regulator 1366 willvent to ambient through outlet 1367. The regulator 1366 is provided witha control knob 1368 accessible on the front panel 1211 for adjusting thepressure. This prevents a pressure above this predetermined pressurebeing established in the airway of the patient or even in the ventilatoritself. So even if everything else fails int he ventilator, this wouldbe the maximum peak pressure which could be provided by the ventilator.

An accessory socket 1371 is provided on the front panel 1211 and isconnected to source gas. The rate of flow of gas through the accessorysocket 1371 is controlled by a needle valve having a knob 1372 (knob J)on the front panel 1211.

The monitor module 1284 which also can be characterized as a waveformanalyzer is provided with a front panel 1381. It also includes anoscilloscope screen 1382 which is mounted in the front panel. The frontpanel also carries a sensitivity knob 1383 calibrated for full scaledeflection in millimeters of H₂ O, a sweep speed knob 1384 calibrated inmillimeters per second, a power off-on switch 1386, a freeze on-offswitch 1387 and an alarm reset push button 1388. The electronicsprovided within the monitor 1204 are substantially conventional and willnot be described.

The monitor module 1204 senses the pressure in the proximal airway ofthe patient and places a trace on the screen 1382. The control knobsprovided on the monitor make it possible to control the sensitivity andthe sweep speed. By way of example, if a patient utilizing theventilator has provided a good blood gas study and with the waveform onthe screen 1382 properly calibrated, the waveform can be frozen. A waxpencil is then used to draw onto the screen 1382 over the frozenwaveform so that a pencil tracing appears on the screen representingthis waveform. This provides a pattern which can be compared by a nurseor other person monitoring the activities of the patient with thewaveform appearing on the screen. If the waveform deviates from thepattern that has been traced on the screen, adjustments can be made onthe ventilator 1201 to provide the desired pattern again. These featuresmake it possible to monitor the operation of the ventilator on thepatient in a very precise manner.

The ventilator 1201 includes a breathing circuit 1391. A block 1392 issecured to the handle 1011 of the accessory module 1203. A ring mount1393 is secured to the block 1392 and carries a nebulizer 1394. Abreathing harness 1396 is provided for connecting the nebulizer 1394into the ventilator module 1202 and to the breathing circuit 1391.

The nebulizer 1394 as shown in FIG. 27 is very similar in certainrespect to the nebulizer 1029 shown in FIGS. 20 and 21. FIG. 27 shows anexploded view of the nebulizer 1394. The nebulizer 1394 is provided withfeatures which make possible long term nebulization rather than theshort term nebulization that can be provided by the nebulizer 1029without the necessity for refilling. The nebulizer 1394 has many partswhich are similar to the nebulizer 1029. Thus the cup-like member 1096can be substantially identical as can seen from FIGS. 20, 1 and 27. Thenebulizer 1394 also includes a quick disconnect cap 1131 of the typedescribed in connection with the nebulizer 1029. It also includes a tee1401 which is bonded to an upwardly extending protrusion 1402 providedon the cap 1131 by a suitable means such as ultrasonic bonding. Abayonet or stamem 1403 is mounted in the tee 1401 and is mounted in sucha way that it extends through the tee and extends downwardly into thesleeve 1138 provided as a part of the cap 1131. A fitting 1406 of asuitable material such as stainless steel is mounted on the lowerextremity of the bayonet or stamem 1403 and is provided with an orifice1407 of a suitable size, as for example, 0.013 of an inch. The fitting1406 carrying an orifice 1407 serves as the stationary part of a valveassembly. The orifice 1407 is adapted to be engaged by a pad 1408 formedof a suitable flexible material such as Silastic which serves as a valvemember of the valve assembly. The pad 1408 is carried by a floatassembly 1409. The float assembly 1409 consists of a sealed annularfloat chamber 1411 formed of an annulus 1412 disposed on the lowerportion of the float assembly 1409. The float assembly 1409 is providedwith a centrally disposed passage 1413 of such a size so that the floatassembly can ride up and down over the cap 1127 and the sleeve 1114.

A suitable number of upstanding posts 1414, as for example, three,spaced 120° apart, are provided on the annulus 1412. The upperextremities of eh posts 1414 are provided with inclined portions 1414aand carry a cylindrical portion 1416 which is provided with acylindrical recess 1417 that receives the pad 1406. The bayonet orstamem 1403 can be connected to a standard intravenous set to supplyliquid as desired to the nebulizer for humidifying the gases. Thissupply id shown as a refill source 1418 in FIG. 26. The flow of theliquid into the nebulizer is controlled by the float assembly 1409. Whenthere is approximately 20 cc's of liquid in the nebulizer, the floatassembly 1409 is raised into a position so that the pad 1408 serving asa valve member engages the orifice 1407 and occludes the same to preventfurther liquid entering the nebulizer. As the nebulizer is used and theliquid level drops, the float assembly 1409 will drop permittingadditional liquid to be supplied to the nebulizer. Thus it can be seenthat automatic nebulization can be provided for the patient over lengthyperiods of time.

In order to permit drugs and other liquids to be introduced into thenebulizer, a drug injection fitting 1419 has been provided on the tee1401. The drug injection fitting 1419 can be capped when not in use. Forexample, during use of the apparatus by a patient, epinephrine can beintroduced through the fitting 1418 and into the liquid in thenebulizer.

The breathing circuit 1391 as shown in FIG. 28 includes a combinationventuri jet and exhalation valve assembly 1036 of the type hereinbeforedescribed. A swivel tee 1421 is mounted on the assembly 1036. One leg ofthe tee 1421 is provided with a suitable patient adapter such as amouthpiece 1422. The other leg of the tee 1421 has a retainer 1423carried thereby. The retainer consists of a plug 1424 which is fittedinto one leg of the tee and the other end carries a ring 1426 which isadapted to be secured to the patient adapter to hold it in place. A pairof fittings 1427 and 1428 are mounted in the tee 1421. The fitting 1427is connected to the tube 1078 which is connected to the remote socket1077 provided on the front panel 1223 and fitting 1428 is connected tothe tube 1086 which is connected to the gauge socket 1087.

In the present application, the combination venturi jet and exhalationvalve assembly 1036 also called a phasitron serves a number of purposes.It serves as an amplifier because it amplifies the stroke volume byentrainment of additional gases with pneumatic clutching. It alsoprovides an exhalation valve. The phasitron 1036 is supplied with gasfrom the tube 1034 which is supplied from the socket 1033. The phasitron1036 is provided with an inlet or entrainment port 848 which is used forentraining additional gases as the gas is introduced into the venturijet from the tube 1034.

As shown in FIG. 28, the phasitron 1036 which is the phasitron shown inFIG. 10 is connected to a corrugated flexible inhalation tube 1198 whichis connected by a coupling 1431 to the inlet port 848. An O-ring 1430forms an air tight seal between the coupling 1431 and the inlet port848. The coupling 1431 is provided with a plurality of circumferentiallyspaced oval-shaped holes 1432. By way of example, four such holes can beprovided spaced 90° apart. A flexible sleeve 1433 formed of a suitableelastomeric material covers the holes 1432 and is disposed betweenspaced-apart annular flanges 1434 formed as a part of the coupling 1431.

Let it be assumed that for some reason that the ventilator 1201 becomeslocked in the inspiratory phase with the exhalation valve remaining inthe closed position. When this occurs, there will be a pressure build upwithin the phasitron 1036 and the venturi jet will no longer entraingases. This increased gas pressure will pass through the openings 1432and inflate the elastomeric sleeve 1433 which serves as a barrel valveand permits the excess pressure to flow to ambient. Thus it can be seenthat the sleeve 1433 serves as an inspiratory fail safe valve.

The large breathing tube 1198 is connected through the water trap 1199of a conventional type to the tee 1401 of the nebulizer 1394. The tee1401 of the nebulizer is connected to a volume regulation manifold inthe form of a cross 1436 as shown in FIG. 29. One leg 1437 of the cross1436 is provided with an inspiratory check valve assembly 1438 whichonly permits gas flow into the tee 1401 of the nebulizer and preventsreverse flow. This check valve assembly includes a spider 1439 and aflapper valve 1441. Any undue pressure buildup in the large breathingtube 1198 will be relieved through the barrel-type valve provided by thesleeve 1433 as hereinbefore explained.

When the patient exhales, the exhaled gases will be discharged throughthe outlet port 819 into a swivel tee 1443 as shown in FIG. 28 which ismounted on the outlet 819. An O-ring 1442 provides an air-tight seal.The swivel tee 1443 is provided with a leg 1444 which has a check valveassembly 1446 mounted therein. The check valve assembly consists of aspider 1447 and a flapper valve 1448. The valve assembly 1446 serves asan expiratory valve safety governor. It will admit ambient air. Thus,for example, if for some reason the ventilator was turned off and no airwas being supplied to the patient, the patient would still be able tobreathe through the valve assembly 1446. Normally during the flow ofexhalation gases through the tube 1197, the flapper valve 1448 will bein a closed position so that the exhaled gases from the patient willtravel down the tube 1197 to the cross 1436 where it is connected to aleg 1451 of the cross as shown in FIG. 29. A valve assembly 1452 isprovided in the leg 1451 and consists of a spider 1453 and a flappervalve 1454. The spider 1453 and flapper valve 1454 are arranged in sucha manner that exhaust gases can only flow inwardly into the cross 1436from the large breathing tube 1197 and not into the breathing tube fromthe cross. Gas passing into the cross 1436 from the tube 1197 will passdownwardly through a leg 1456 of the cross into the elastomeric bag1196. Ass soon as the bag 1196 becomes overfilled, the additionalexhaust gases will be discharged through the ambient purge port providedby another leg 1457 of the cross 1436 through a valve assembly 1458consisting of a spider 1459 and a flapper valve 1461.

As hereinbefore explained, the bag 1196 is provided to provideadditional inspiratory gases during peak inspiration. Rather thanstarving the patient during entrainment, gas will be pulled through thevalve assembly 1452 into the large breathing tube 1197. By the provisionof such a reservoir by use of the bag 1196, there is a partialrebreathing of exhaled gases. By providing such a reservoir, it ispossible to ventilate at rates up to 30 to 50 liters a minute.

An exploded view of the failsafe governor alert 1248 is shown in FIG.30. As shown therein it consists of a body 1466 formed of a suitableplastic. The body is provided with a cylindrical portion 1467 whichadjoins a truncated conical portion 1468. An inlet 1469 is formedintegral with the tapered or conical potion 1468 and is provided with aninlet flow passage 1471 which opens through the inlet 1469 and into achamber 1472 within the cylindrical portion 1467. The body 1466 is alsoprovided with an upwardly extending rim 1473. The rim 1473 is providedwith a cylindrical recess 1474 which opens into the chamber 1472. Aplurality of threads 1476 are provided on the outer surface of thecylindrical portion 1467 so that the governor alert 1248 can be threadedinto the front panel 1211. A gate valve 1477 formed of a suitablematerial such as Teflon is provided and is adapted to seat against theinterior of the conical portion 1468. The gate valve 1477 is providedwith an inclined or tapered surface 1478 which generally corresponds tothe incline of the conical portion 1468 which serves as a valve setagainst which the gate valve 1477 can seat. A generally semi-sphericaldepression or recess 1479 is formed in the surface of the gate valve1477 facing away from the inlet passage 1471. A valve stem 1481 alsohaving a semi-spherical rounded end is adapted to set in the depressionor recess 1479 and extends outwardly from the gate valve 1477.

Means is provided for isolating the valve stem 1481 from the gate valve1477 and consists of a pair of o-rings 1482 formed of a relatively softrubber as for example, rubber having a hardness of approximately 40durometers. The o-rings 1482 frictionally engage the valve stem 1481 andare placed one above the other and area adapted to engage the outersurface of the gate valve 1477 in such a manner so as to retain thelower extremity of the valve stem 1481 out of engagement with thedepression or recess 1479 but still permitting the gate valve 1477 topivot with respect to the valve stem. Means is provided for yieldablyurging the valve stem into the depression or recess 1479 of the gatevalve and consists of a spring 1483 concentrically mounted on the valvestem and having one end engaging a washer 1484 overlying the o-rings1482 and having the other end adapted to be engaged by a nut 1486. Thenut 1486 is threaded into a central portion 1487 of a spider 1488. Thespider 1488 is mounted in the recess 1474 and retained therein by aclamping ring 1489.

The failsafe governor alert valve assembly 1248 serves two functions. Itserves to provide a pressure relief above a predetermined pressure thatis determined by the setting of the nut 1488 and its engagement with thespring 1483. It vents to atmosphere whenever the gas pressure againstthe gate valve 1477 exceeds the pressure which is sufficient to overcomethe force of the spring 1483. At the same time the valve assembly 1248is constructed in such a manner so that as when gas is being relievedunder pressure through the valve assembly 1248 an audible alarm isprovided by the periodic chatter of the gate valve 1477 on its seat.This chatter has been found to be particularly reliable and audiblebecause of the fact that the gate valve 1477 has been isolated from thevalve stem 1481. The valve assembly has been made particularlyefficacious because of the isolation of the valve stem 1483 from thegate valve 1477 by the use of the two O-rings 1432. The audible signalgiven off by the alarm is very distinguishable. The outer clamping ring49 provided serves as an amplifier to increase the intensity of thealarm. In addition, the clamping ring 49 physically protects the valvestem 1481.

Another embodiment of a breathing head assembly is shown in FIG. 31 andis one which is utilized for providing differential ventilation. Thisbreathing head assembly 1502 consists of two separate combinationventuri jet and exhalation valve assemblies or phasitrons 1036 which arecoupled together with two tee assemblies 1502 and 1503. The tee assembly1502 is connected to the inlet fittings 848 of the phasitrons 1036whereas the tee assembly 1503 is connected to the exhalation outlets 819of the phasitrons 1036.

The tee assembly 1502 is similar to the coupling 1431 provided in FIG.28. The tee assembly 1502 includes a tee 1504. The tee 1504 is providedwith legs 1506, 1507 and 1508. The legs 1506 and 1507 are provided witho-rings 1509 seated within annular recesses 1511 provided in the legs.These o-rings 1509 are adapted to frictionally engage and seat inannular recesses 1512 provided on the exterior surfaces of the inlets848 on the phasitrons 1036. In this way, fluid-tight connections aremade between the inlets 848 and the tee 1504.

The tee 1504 is also provided with a fitting 1513 which is adapted toreceive a cap (not shown) which may be removed to introduce drugs andthe like into the breathing circuit. The remaining leg 1508 of the tee1504 is adapted to receive one end of a coupling 1516. The coupling 1516is similar to the coupling 1431 shown in FIG. 28. The coupling isprovided with an annular recess 1518 in one end which carries an o-ring1517. The o-ring is adapted to snap into a recess 1519 provided on theleg 1508. The coupling is provided with a pair of spaced apart parallelannular flanges 1521. The coupling is also provided with a plurality ofoval-shaped openings 1522 which are spaced circumferentially around thecoupling. An elastomeric sleeve valve 1523 is carried by the coupling1522 and is disposed between the flanges 1521. The other end of thecoupling 1516 is connected to the large breathing tube 1198. The inletfitting 866 of the phasitron 1036 are connected to the tubes or lines1034 and 1078 which are connected respectively to the sockets 1033 and1077.

The tee assembly 1503 is constructed of a tee 1526 having legs 1527,1528 and 1529. The legs 1527 and 1528 are provided with o-rings 1531seated in annular recesses 1532. The o-rings 1531 are adapted tofriction and seat in recesses 1533 provided on the outlet fittings 819of the phasitrons 1036 and form fluid-tight connections therewith. Theleg 1529 is provided with an annular recess 1534 on the interior surfacethereof. Another tee 1536 is provided having legs 1537, 1538 and 1539.An o-ring 1541 is mounted in an annular recess 1542 in the outer surfaceof the leg 1537. The o-ring 1541 is adapted to seat in the annularrecess 1534 provided in the leg 1529 of the tee 1526. The other leg 1538is adapted to receive the large exhalation hose 1197. A flapper valve1543 is provided in the leg 1539 and is retained in position by a spider1544 supported in the tee 1539 by a retainer ring 1546. The gauge tube1086 which is connected to the socket 1087 is connected to the fitting821 provided on one of the phasitrons 1-36.

From the foregoing it can be seen that the inlets of the two phasitrons1036 have been interconnected by a tee to interconnect the inspiratoryfailsafe valves. Essentially the same thing has been done on theexpiratory side where the expiratory failsafe ports of the phasitrons1036 have been interconnected.

The dual phasitron assembly 1501 shown in FIG. 31 has numerousapplications where it is desired to utilize differential ventilation.Let it be assumed, for example, that a patient has a good lung and a badlung, as for example, from a car accident in which a steering wheelinjured one lung and the other lung was satisfactory. When such is thecase it is desired to ventilate the damaged lung and to do very little,if anything, for the other lung. When this is the case, the line 1034which is connected to the phasitron 1036, is connected to the inlet 866of the phasitron 1036 which is to be connected to the damaged lung. Acounterpulsing line 1078 can be connected to the other inlet 866 of theother phasitron 1036. The good lung would be connected to the phasitron1036 which has the normal phasitron line 1034 connected thereto. Thedamaged lung, on the other hand, would be connected to the phasitronhaving the counterpulsing line 1078 connected thereto.

By use of the controls of the ventilator as hereinbefore described andby adjusting the IE ratio it is possible to control the damaged lungwith both a frequency rate and a desired IE ratio. The damaged lung canbe treated until it stabilizes while providing normal ventilation forthe other lung.

Another advantage of such a breathing head is that it makes it possiblefor a surgeon to operate on one lung and to still ventilate the otherlung. Also with respect to the lung on which the physician is operating,he does not want that lung to collapse. The present breathing head wouldmake is possible to pulse a lung and keep the lung inflated and aeratedat any desired level while the surgeon was operating on the same, as forexample, excising a segment of the lung.

Operation of the ventilator shown in FIGS. 25 through 31 may now bebriefly reviewed as follows. The ventilator 1201 as hereinbeforedescribed is a ventilator which can provide conventional ventilationthrough conventional time cycling and which also can provide diffusiveventilation using convection. With these two basic types of ventilationbeing provided, the ventilator 1201 also has many other features. Forexample, it is provided with a demand CPAP and it is provided with amanual override. In addition, nebulization is also provided.

The expiratory failsafe exhalation valve assembly 1446 mounted on thecombination venturi jet and exhalation valve assembly 1036 is inrelatively close to the proximal airway so there is very little deadspace. This is particularly important in protecting against a gas sourcefailure. When a gas source failure would occur, the patient would firstempty the reservoir bag 1196 and as soon as this gas has been exhausted,the expiratory failsafe valve opens to continue to permit the patient tobreathe by bringing in ambient air. Thus by providing this expiratoryfailsafe valve 1446, protection has been provided against inspiratoryfailure, expiratory failure and a gas source failure.

Another safety feature provided in the ventilator is the use of theelastomeric safety loop formed by the retainer 1423 which serves toprevent disconnects between the patient adapter 1422 which can be in theform of a mouthpiece or endotracheal tube and the swivel tee 1421 whichis connected to the combination venturi jet and exhalation valveassembly 1036. In addition, the plug 1424 of the retainer 1423 can beremoved from the tee 1421 and the opening used. This opening can beutilized in conjunction with a bronchial scope. Also other tools can beintroduced through the opening, as for example, tools for excisingtissue while at the same time providing ventilation to the patient.

As hereinbefore explained, the counterpulsing flow which is provided inthe ventilator provides a pulsive flow which is 180° out of phase withthe flow provided by the timing circuit. The flows of gases from thecounter-pulsing circuit and the timing circuit pass through a largeorifice at the top of the swivel tee 1421 and through the physiologicalairway port of the phasitron. The entrance of gas through this fittingdumps fresh gas into the combination venturi jet and exhalation valveassembly 1036. It also washes out any rebreathing gases. As alsohereinbefore explained, the counterpulsing circuit makes it possible toprovide differential ventilation for the two lungs of a patient.

Upon operation of the counterpulse cartridge 1321 a subambient pulse isdelivered to the counterpulse socket 1077 which is delivered to theswivel tee 1421 carried by the combination venturi jet and exhalationvalve assembly 1036. In order to increase the effectiveness of thesubambient pulse, a venturi body may be provided. It is mounted into theassembly 1036 to provide a powerful suction apparatus by providing apressure of -30 to -40 centimeters of water in the patient airway. Theventuri body by narrowing the passage provides more effective venturiwith greater velocity. This feature is particularly useful with smallbabies and with small animals to overcome resistance and draw air out ofthe lungs. The subambient pressure provides a washout so as to limitrebreathing of gases.

In FIGS. 32, 33 and 34 there are shown clinical waveforms which havebeen obtained utilizing the ventilator shown in FIGS. 25 through 30. Asnoted, the waveforms have been plotted in seconds and centimeters of H₂O.

The curve 1551 in FIG. 32 shows a diffusive ambulator pattern whichstarts at a baseline of zero and is provided with a plurality of peaks1552 which show oscillation which gradually increases in centimeters ofH₂ O until pneumatic clutching occurs which causes the pressure rise tolevel off as shown in the curved portion 1551. This pneumatic clutchingoccurs at a predetermined value of centimeters of H₂ O, for example,between 10 and 15 psi. A variable frequency is provided with anindependent variable IE and with the amplitude controlled by a knob 1352(knob B). The frequency is controlled by knob 1326 (knob A). Byexamining FIG. 32, it can be seen that the pneumatic clutching occurs atapproximately the point where the amplitude reaches a maximum which onthe curve would be approximately 12 centimeters of water. This maximumamplitude is determined by the setting of the knob 1352. If knob 1352 isrotated counterclockwise to open it up further, the amplitude isincreased to higher values, as for example, to 30 or 40 centimeters ofwater. Typical settings of the knob 1352 for neonates, would range from15 to 20 psi, for pediatrics 20 to 25 psi, for adults 20 to 35 psi andfor giants 35 to 40 psi. The frequency 1326 is set to the appropriatefrequency. The IE ratio is also set at an appropriate value, typicallyit can be one-to-one. To obtain percussion, it can range from 1:2 to1:3.

As shown in FIG. 2, the oscillations can continue for a suitable periodof time, as for example, approximately 15 seconds. At this time, thetransition delay cartridge 1271 takes over in the manner hereinbeforedescribed so that pressure in the patient airway drops down to near thebaseline as shown by the portion of the curve 1551b in FIG. 32. Thisbaseline is established by the demand CPAP regulator 1217 under thecontrol of knob 1351. The demand CPAP can be turned off in which casethe baseline is at ambient or zero centimeters of water as shown by thecurve in FIG. 32. However, it should be appreciated that, if desired,the baseline can be set at any desired value, as for example 5 or 6centimeters of H₂ O.

The conventional ventilator is then programmed for an inspiratory timewhich is determined by the adjustment of the knob 1301 (knob D) and bythe inspiratory flow by the adjustment of the knob 1296 (knob E) whichwill determine the pressure rise as a conventional tidal volume isdelivered into the lungs of the patient. After the tidal volume isdelivered to the patient's lungs, the pressure drops to the baseline anda pause can be introduced by adjustment of the knob 1288 (knob F). Thispause can range from various periods of time, as for example, from 1second to 4 or 5 seconds typically in the range of approximately twoseconds. The length of the pause determines the time that is permittedfor blood to be returned into the pulmonary circuit by the patient'sheart.

In the curve 1551 shown in FIG. 2, the oscillations can continue for asuitable period of time, as for example, approximately 15 seconds. Atthis time, the transition delay cartridge 1271 takes over in the mannerhereinbefore described so that pressure in the patient airway drops downto near the baseline as shown by the portion of the curve 1551b in FIG.32. This baseline is established by the demand CPAP regulator 1217 underthe control of knob 1351. The demand CPAP can be turned off in whichcase the baseline is at ambient or zero centimeters of water as shown bythe curve in FIG. 32. However, it should be appreciated that, ifdesired, the baseline can be set at any desired value, as for example 5or 6 centimeters of H₂ O.

The conventional ventilator is then programmed for an inspiratory timewhich is determined by the adjustment of the knob 1301 (knob D) and bythe inspiratory flow by the adjustment of the knob 1296 (knob E) whichwill determine the pressure rise as a conventional tidal volume isdelivered into the lungs of the patient. After the tidal volume isdelivered to the patient's lungs, the pressure drops to the baseline anda pause can be introduced by adjustment of the knob 1288 (knob F). Thispause can range from various periods of time, as for example, from 1second to 4 or 5 seconds typically in the range of approximately twoseconds. The length of the pause determines the time that is permittedfor blood to be returned into the pulmonary circuit by the patient'sheart.

In the curve 1551 shown in FIG. 32 there is a convective drop to thebaseline as represented by the portion 1551b of the curve 1551, aconvective rise to the maximum pressure as shown by the portion 1551cand thereafter a convective drop back to the baseline represented by theportion 1551d of the curve 1551. Thereafter, there is a portion 1551e ofthe curve 1551 during which counterpulses are being introduced whichgreatly enhance diffusion within the lung. As shown in FIG. 2, thiswaveform is then repeated as the ventilator continues to operate.

The waveform pattern which is shown in FIG. 32 is a typical patternwhich could be utilized on neonates, pediatrics and adults where arespiratory distress syndrome is present. This is the unique situationwhere the lung is damaged or incomplete caused by accidental trauma,infection or by the undeveloped nature of a premature baby's lungs. Thiswaveform shown in FIG. 32 represents a combination of diffusive andconvective ventilation. In the portion 1551a of the curve 1551 there ishigh frequency diffusive ventilation at the rate of 300 to 600oscillations a minute after which convective ventilation takes place anddrops the pressure back down to the baseline permitting the patient toexhale to move the gases out of the lungs of the patient after which thelung is filled up again with a constant flow of gas to provide aconventional tidal volume to the patient with a counterpulse on it whichhelps to provide additional diffusion. After which this tidal volume isreleased from the lung as shown by the portion 1551d of the curve.Thereafter, the curve is repeated by high frequency diffusiveventilation followed by convective ventilation and this is repeated. Bythis combination of diffusive and convective ventilation, it can be seenthat during the diffusive ventilation, the gases are mixed up in thelung by the high frequency ventilation after which these gases aredumped out of the lung in portion 1551b and thereafter the lung israpidly refilled with a tidal volume and then emptied again and thenheld in a pause for a period of time to permit the blood to come backinto the lungs.

In FIG. 33 there is shown a pattern which could be utilized with apatient having obstructive pulmonary disease. In such a case, it isimportant to obtain good mixing of the gases. In this situation, theconvective or conventional ventilator is utilized to produce a pauseonly. A tidal volume is not delivered. The frequency is selected byadjustment of the knob 1326 (knob A) and the knob 1352 (knob B) isadjusted to provide a high amplitude. Thus as shown in the curve 1556 inFIG. 33 as soon as the respirator cycles on, it begins to oscillate andthe amplitude increases rapidly until pneumatic clutching is achieved atthe pressure set by the knob 1352 and is represented by the portion ofthe curve 1556a. In the portion of the curve 1556a, gas is delivered inincrements to the patient preventing the gas from flowing in and outduring the time that the amplitude is being increased. The portion 1556aof the curve 1556 shows that there are pulses with a pressure rise and apressure drop followed by a pressure rise and a pressure drop. Each timethe pressure drops, the pressure is equilabrated in the lung. Thisprovides a relatively smooth curve which is substantially in the form ofa sign wave and provides excellent intrapulmonary distribution in thelungs of the patient. By providing such high frequency pulses of gases,it is possible for the ventilator to accommodate various types of lungproblems, as for example, puncture wounds, pneumothoraes, interstitialair leaks and the like. By such an approach, it is possible for theventilator to compensate for massive air leaks in the lungs and stillventilate the lungs. Thereafter the pressure drops down to the baselineas represented by the portion 1556b of the curve 1556 after which thereis a pause represented by the portion 1556c of the curve. Thereafter thesame waveform is repeated. In FIG. 33 the knob 1352 was adjusted togradually increase the flow rate to increase the amplitude up toapproximately 35 centimeters of H₂ O. As can be seen, the convectiontidal volume delivered by the conventional ventilator portion of theventilator has been removed and all that is provided is diffusive highfrequency ventilation. Counterpulsing, however, is still present as canbe seen by the small pulses superimposed on the waveform.

In FIG. 34 there is shown another waveform 1557 which has beenparticularly efficacious on neonates. As shown in FIG. 34 as theventilator is turned on, high frequency oscillations are supplied to thelung of the patient as represented by the curve portion 1557a until thepneumatic clutching pressure is reached at approximately 10 centimetersof H₂ O at which time there is delivered a short tidal volume asrepresented by the curve portion 1557b after which there is a drop tothe baseline as represented by the curve 1557c. After a pause asrepresented by the curve portion 1557d of a suitable period, as forexample, two seconds, the waveform is repeated until the right hand sideof the waveform shown in FIG. 34 at which time the knobs 1352 and 1326are turned off so that all that remains is convective ventilation as isrepresented by the peaks 1557b. These peaks are controlled by the knobs1301 (knob D) and knob 1296 (knob E).

The adjustments of the knobs on the ventilator have been provided suchthat when the knobs are in a 12:00 o'clock position, the ventilator willfunction in a normal manner. Thus if an operator is unsure or becomesconfused as to the adjustment of the knobs, the ventilator can beoperated in a safe manner by turning all the knobs to the 12:00position.

Another embodiment of the sleeve check valve or flow obtunder shown inFIG. 19 is shown in FIGS. 35 and 36. This sleeve check valve 1561, whichalso can be called a flow obtunder, consists of a cylindrical body orhousing 1562 which has disposed therein a stem 1563. The cylindricalhousing 1562 is provided with a cylindrical recess 1564 which is incommunication with a passageway 1566 extending through a cylindricalextension 1567. The extension 1567 is provided with circumferential ribs1568 spaced longitudinally of the extension and which are adapted tofrictionally engage flexible tubing of a suitable type such as plastictubing which is pushed onto the extension 1567. The housing 1562 also isprovided with an annular recess 1569 which adjoins a chamfer 1571 makinga graduated transition between the annular recess 1569 and thecylindrical recess 1564.

The stem or body 1563 is provided with a radially extending flange 1572which is adapted to be secured to the cylindrical 1562 by suitable meanssuch as ultrasonic welding. The stem or body 1563 is also provided withcylindrical portions 1573 and 1574 which are adapted to seat within thecylindrical recess 1569 and within the cylindrical recess 1564respectively. The stem or body 1563 is also provided with cylindricallands 1576 and 1577 which are spaced longitudinally away from the flange1572. For reasons hereinafter described, the land 1576 is of a slightlylarger diameter than the land 1577. By way of example, the land 1576 canhave a diameter of 0.215 inches and the land 1577 can have a diameter of0.205 inches. The stem or body 1563 is provided with a radiallyextending lip 1578 on the outer extremity of the same. The stem or body1563 is also provided with a cylindrical extension1579 on the sideopposite the side the lands 1576 and 1577 are disposed. The extension1579 is provided with spaced apart annular ribs 1581 which are adaptedto be engaged by a flexible hose or tube (not shown) pushed over theextension 1579. The extension 1579 is provided with a flow passage 1582which extends longitudinally of the stem or body 1563 into the region ofthe lands 1576 and 1577. A cross hole 1583 is provided in the stem orbody 1563 between the lands 1576 and 1577 which opens into a pair ofarcuate recesses 1584 and 1586 extending circumferentially of the stemor body 1563. It can be seen that the recesses 1584 and 1586 are of sucha length so that there remain raised portions or ribs 1587 (see FIG. 36)extending between the lands 1576 and 1577. The recesses 1584 and 1586are formed so that the portion of the recess adjacent the land 1576 incross section is in the form of a quarter circle 1584a and that theportion of the recess adjacent the land 1577 is in the form of aninclined plane 1584 which adjoins a vertical surface 1584c. The surface1584c adjoins the circular portion 1584a.

An elastomeric sleeve 1589 is disposed on the stem or body 1563 and isformed of a suitable material such as rubber. It is sized in such amanner so that it makes a relatively tight fit with the land 1576 but isrelatively loose with respect to the land 1577. The sleeve 1589 isprevented from being blown off of the stem or body 1564 by thecircumferential lip or flange 1578 and is therefore captured.

Assuming that a gas is introduced into the passage 1582 from theextension 1579, the gas will flow inwardly of the passage 1582 and willexit through the cross holes 1583. The gas will take the path of leastresistance and will flow over the inclined ramp surface 1584b and thenout circumferentially around the sleeve 1589 and then the land 1577. Gasreleased by the sleeve will then pass out through the passage 1566provided in the cylindrical body 1562. It is has been found that byconstructing the sleeve check valve in this manner, fluttering ordancing of the sleeve 1589 at high frequencies in a range of 1500 to2000 times a minute has been eliminated. This is made possible becausethe sleeve is captured by the land 1576 and is held stationary whileleaving the other end of the sleeve to flex to permit the escape of thegas from the cross holes 1583. In order to prevent flaking off of thedistal extremity of the sleeve 1589, it has been found that it isdesirable to radius the inside distal extremity of the sleeve to providea curved surface 1591. With such a construction it has been found thatthe sleeve check valve 1561 can operate under high frequency conditionsfor long periods of time.

In FIGS. 37 and 38, there is shown a normally open flow/timing cartridge1601 which is particularly useful in the present invention. It consistsof a manifold body 1602 and a cartridge body 1603. The manifold body1602 is generally cylindrical as shown and is provided with a radiallyextending flange 1604 provided on one extremity thereof. The flange 1604is provided with an annular recess 1605.

The manifold body 1602 is provided with three threaded bores 1606, 1607and 1608 disposed circumferentially around the circumference of the body1602 adjacent the rear extremity of the body 1602. As shown in thedrawings, the bores 1606 and 1607 are spaced 180° apart with respect toeach other whereas the bore 1608 is disposed between the bores 1606 and1607 and is spaced 90° therefrom. The bores 1606 and 1607 are incommunication with a flow passage 1609 extending diametrically of thebody. The flow passage 1609 is in communication with a flow passage 1611which can be identified as a first flow passage for the manifold body1602. The flow passage 1611 extends at right angles to the flow passage1609 and opens into a threaded bore 1612 provided in an externallythreaded cylindrical extension 1613 provided on the rear extremity ofthe body 1602. Another flow passage 1614 is provided in the body 1602and is in communication with the threaded bore 1612 and is incommunication with the bore 1608. Fittings 1616 are provided in certainof the bores 1606, 1607 and 1608 and are adapted to be connected toflexible tubes of the type hereinbefore described.

The manifold body 1602 is also provided with another threaded bore 1617extending radially of the body and spaced forwardly of the bores 1606and 1607. It is also provided with a fitting 1616. The bore 1617 is incommunication with a flow passage 1618 extending radially of the boreand is in communication with another flow passage 1619 extendingperpendicular thereto and which opens through the forward extremity ofthe body 1602 into a dish-shaped recess 1621. The flow passage 1619 canbe identified as a second flow passage for the manifold body 1602.

The cartridge body 1603 has a generally bell-shaped configuration. It isprovided with a port or flow passage 1623 on its forward extremity whichis axially aligned with the cartridge body and is in communication witha generally bell-shaped plenum chamber 1624 which opens through the rearof the cartridge body 1603. The flow passage 1623 can be identified as afirst flow passage for the cartridge body 1603. The cartridge body isalso provided with a side port 1626 mounted therein. The ports 1623 and1626 are configured in such a manner so that quick disconnect fittingsof the type hereinbefore described can be utilized in conjunction withthe same.

A poppet valve assembly 1627 is disposed within the bell-shaped chamber1624 and is engaged by the manifold body 1602 which is removably securedto the cartridge body 1603 by suitable means such as a C-type lock ring1628 which engages the rear side of the flange 1604 of the manifold body1602 and an annular inwardly extending lip 1629 provided at the rearextremity of the cartridge body 1603. The poppet valve assembly 1627includes a circular diaphragm 1631 formed of a suitable material such asa rubber which has a bead 1632 formed on its outer margin which iscaptured between the manifold body 1602 and the cartridge body 1603. Asshown, this bead 1632 is disposed in the annular recess 1605 of theflange 1604 and seats against a shoulder 1633 of the cartridge body1603. The shoulder 1633 is provided with a raised rounded lip 1634 whichalso serves to capture the bead 1632.

The diaphragm 1631 is provided with a curved semi-circular portion 1636which is relatively thin to permit flexing of the diaphragm. Thediaphragm is also provided with a central circular thicker portion 1637which is of a size so that it is adapted to fit within the dish-shapedrecess 1621 of the manifold body 1602. The central portion 1637 isprovided with a plurality, in this case, four cylindrical projections orfeet 1638 which are uniformly spaced on the surface of the centralportion 1637. The underside of the diaphragm 1631 is in communicationwith a flow passage 1619 of the manifold body 1602. At least a portionof the flow passage 1619 can be considered to be a second flow passagefor the cartridge body 1603.

The central portion 1637 is also provided with a centrally disposedcylindrical protrusion 1639 on the side opposite on which theprojections or feet 1638 are disposed. The centrally disposed protrusion1639 serves as a seat for a cam button 1641 of a suitable material suchas plastic. The cam button is provided with a recess 1642 which receivesthe protrusion 1639. It is also provided with a radially extendingflange 1643 which terminates short of the semicircular portion 1636 ofthe diaphragm 1631. The cam button 1641 extends through a ring or washer1644 formed of a suitable non-corrosive metal such as brass or stainlesssteel. The forward extremity of the cam button engages a diaphragm seal1646 formed of a suitable material such as rubber. The seal 1646 isprovided with an outer annular bead 1647 which is captured between thewasher 1644 and a shoulder 1648. The washer 1644 is held in place by aC-type lock ring 1649 which engages an annular recess 1650 provided inthe cartridge body 1603.

An elastomeric percussion pad 1651 is disposed in the ring 1644 betweenthe seal 1646 and the top of the cam button 1641 and has a diameterslightly greater than that of the cam button. This pad can be loadedwith 15 to 20% graphite so as to provide a slippery permanent shockabsorbing and compression absorbing interface between the cam button 641and the disc 1646. Thus, the bottom surface of the seal 1646 isprotected from abrasion by compression and stretching of the seal bymovement of the cam button 1641.

A poppet or poppet valve plunger 1652 is provided which is seated overthe disc 1646. The valve plunger or poppet 1652 is made of a suitablematerial such as a relatively hard plastic and is provided with a stem1653. The stem 1653 is generally cylindrical in form and extends atright angles or forwardly from a radially extending flange or poppethead 1654. The flange 1654 is provided with a circular recess 1656facing rearwardly and which has disposed therein a pad 1657. The pad1657 is formed of a suitable elastomeric with a 15 to 20% loading ofgraphite.

The pad 1657 has a diameter greater than that of the cam button 1641 andserves to protect the seal 1646 from abrasion caused by compression andstretching of the diaphragm seal between the poppet head 1654 and thecam button 1641.

The valve plunger 1652 is provided with an annular recess 1658 on theupper extremity of the stem 1653 and has mounted therein an O-ring 1659.The O-ring 1659 is adapted to form a sealing engagement with an annularinclined valve seating surface 1661. Compression of the O-ring islimited by limiting the travel of the plunger 1652. The plunger 1652cannot travel beyond the point where the head 1654 strikes the shoulder1662. A pilot bore or chamber 1663 adjoins the valve seating surface1661 and the plenum chamber 1624.

In the event that the diaphragm seal 1646 is breached, vent holes 1664to ambient in the cartridge body 1603 are sufficient to limit thepressure rise caused by on-servoing against the forward side of themaster diaphragm 1631. These vent holes 1664 are sufficiently large toassure there is sufficient venting to negate any possible hightemperature stall as the diaphragm becomes more pliant at hightemperatures as well as potential hard open servoing.

The cartridge 1601 is provided with a needle valve assembly 1666 whichis threaded into the bore 1612. It is provided with a control knob 1667for adjusting the position of a needle valve 1668 to control the flow ofgas from the passage 1611. The cartridge 1601 can be supported in asuitable manner such as by mounting it on a panel 1669 and securing itthereto by a nut 1671 as shown in FIG. 37.

Operation and use of the normally open flow/timing cartridge 1601 shownin FIGS. 37 and 38 may now be briefly described as follows. Let it beassumed that the cartridge 1601 is in its normally open position. Inthis position gas may flow from the port 1626 to the port 1623 or viceversa. Let it now be assumed that it is desired to interrupt this flowof gas from the port 1626 to the port 1623. This is accomplished byapplying gas under pressure to the servo port 1617. This gas passesthrough the passages 1618 and 1619 to the underside of the diaphragm1631 to cause it to rapidly move the poppet valve in the form of theO-ring 1659 into rapid engagement with the seat 1661 to prevent furtherflow of gases from the port 1626 to the port 1623.

Now let it be assumed that it is desired to move the cartridge 1601 fromthe closed position to its normally open position. To accomplish this,the pressure from behind the diaphragm 1631 is held down gradually. Assoon as there has been some bleed down, the poppet valve 1652 will havea tendency to open at least a slight amount. This permits the pressureof the gas which is in the port 1623 to act upon the very small area ofthe end of the poppet valve 1652, as for example, approximately onequarter of an inch in diameter and to act upon the diaphragm 1631 whichbecause of its much larger area would cause the poppet valve to snaprapidly to a completely open position. Conversely when pressure isapplied to the servo port 1606, the poppet valve 1652 is cammed rapidlyinto a closed position. This snap opening and closing of the poppetvalve 1652 is created because of the large differential between thequarter of an inch diameter surface represented by the O-ring 1659 atthe top of the poppet valve and the one-half inch diameter surface ofthe diaphragm. In other words by providing this large differential it ispossible to obtain almost instantaneous opening and closing of thepoppet valve. This rapid opening and closing makes possible very highfrequency of operation of the cartridge.

The cartridge 1601 will work over a very wide range of operationalpressures because the same operational pressure is used in the inletport 1623 as in the servo port 1617. Thus, for example, it is possibleto operate this type of cartridge with pressures ranging from 2 poundsto 100 pounds per square inch. As hereinafter explained, it is thiscapability of the cartridge which makes it possible to operate down tothe neonatal range and up to an adult range and also makes it possibleto provide a respirator which has a single control.

There are a number of features in the construction of the cartridge 1601which makes this long life possible. As pointed out above, the poppet orvalve plunger 1652 has been provided with an insert pad 1657 which isprovided with graphite. This pad has a diameter which is slightlygreater than that of the compression of the cam button. There istherefore provided a slippery permanent shock and compression absorbinginterface between the cam button 1641 and the valve plunger 1652. Thisshock and compression absorbing interface also minimizes abrasion causedby compression and stretching of the diaphragm.

From the construction shown it can be seen that the poppet 1652 residesin a cylindrical chamber with a pilot bore 1663 rising from the inclinedvalve seat 1661. The pilot bore above the valve seat provides acentering effect for alignment purpose as the poppet stem 1653 carryingthe O-ring 1659 moves towards the closed position. Gas flowing into theinlet port 1623 passes around the O-ring and causes centering alignmentof the poppet assembly. Flow against the O-ring provides an openingpiston effect against the poppet carrying the O-ring. The outlet port1626 is disposed so that the gases exit around the stem and also causethe stem to be held in alignment within the conical valve seat limits.

This arrangement of the poppet assembly inhibits erratic functioning ofthe poppet valve. Adequate clearance is provided between the O-ring 1659and the valve seat 1661. A definitive pressure drop across the O-ring1659 which serves as a valve gate is maintained during all flowconditions to maintain full flutter-free opening as well as an openingservoing force. These requirements are satisfied by the cylindrical bore1663 rising from the valve seat 1661 which is inclined at a 45° anglewith sufficient height to accommodate the full stroke with a diameterthat allows maximum flow while centering the poppet stem carrying theO-ring within the conical seat area. The differential diameter betweenthe O-ring gate valve and the diaphragm seal is at least 1 to 2 causinga pressure buildup in the poppet cylinder at the point of opening toback servo the diaphragm seal to allow the poppet to ride against theascending diaphragm dome. Lateral movement of the O-ring gate is limitedby the pilot bore 1663 thereby capturing the valve gate so that itremains in alignment during its stroke.

The amount of O-ring compression has been limited. When the closingservoing pressures exceed 25 psi (which is beyond the normal operatingpressure range) the poppet head 1654 reaches the shoulder 1662 whichlimits further forward travel and further O-ring compression. The travelof the servoing master diaphragm 1631 is limited by progressivediaphragmatic unloading as the semi-circular portion or convolution isflexed. This flexing is limited by the geometry of the bell-shapedchamber 1624.

The present design utilizing the elastomeric graphite filled pads 1651and 1657 permits the use of a thin low durometer diaphragm seal 1646 torapidly respond to both mechanical opening and closing pressures undervarious working conditions while still providing the necessaryresistance to abrasion so as to provide a long working life. By keepingthe poppet 1652 centered, the friction between the poppet head rim andthe walls of the chamber are minimized. The cartridge 1601 makespossible the delivering of pulsatile stroke volumes at a selectedopening and closing ratio and time as inlet pressures are increased.

From the arrangement hereinbefore described it can be seen that thepoppet 1652 is cellularized in its chamber by a captured diaphragm seal1646 which in turn is actuated downward by a cam button 1641 under thecontrol of the master servoing diaphragm 1631. While closing ismechanical in nature, opening is caused by a pressure rise in the plenumchamber 1624 acting to cause a yield of all components of elastomericclosing. Piston effects acting upon differential servoing areas balanceoperations between servoing and valving actions as operational pressuresare changed. The flight path of the poppet valve gate captured on thepoppet assembly is precisely guided within its valve seat cone by thepilot bore 1663 above the valve seat.

By constructing the cartridge 1601 in the manner hereinbefore described,it has been found that diaphragm seal life has been greatly prolonged.The cartridge can operate at high frequencies with very little noise.Peak flow restrictions are overcome and stalling is inhibited. Pressuresranging from 15 to 100 psi are readily accommodated. Cylic operationfrom 1 to 1800 cycles per minute could be readily accommodated.Sufficient operational stroke and clearance of the poppet valve isprovided to permit back servoing in proportion to outflow within a flowrange from 5 to 200 liters per minute. Valve opening and closing issubstantially instantaneous to provide maximum flow during the valveopen interval. It has been found to be capable of operating forprolonged periods of time at high frequency oscillation without selfdestructing. Billions of cycles of operation can be performed beforeoverhaul is required.

Another embodiment of the normally open flow/timing cartridge is shownin FIGS. 39 and 40. As shown therein, the cartridge 1676 consists of amanifold section 1677 and a cartridge 1678 both of which combinedperform the same function as the cartridge 1601. The manifold section1677 is provided with a cylindrical manifold body 1679 provided withthree threaded bores 1681, 1682 and 1683 which are arranged in the samemanner as in the bores 1606, 1607 and 1608 in the manifold body 1602.They are connected by passages 1684, 1686 and 1687 in the same way thatpassages 1609, 1611 and 1614 interconnect the bores 1606, 1607 and 1608.The passage 1686 serves as the first passage for the manifold section1677. In a similar manner, the manifold body 1679 is provided with athreaded bore 1688 which extends into an exteriorly threaded protrusion1689. The bore 1688 is in communication with the passages 1686 and 1687.The manifold body 1679 is also provided with another threaded bore 1691which is offset longitudinally as well as circumferentially of the bores1681, 1682 and 1683. The bore 1691 is in communication with a flowpassage 1692 which extends at right angles to another flow passage 1693extending axially of the manifold body 1679. The flow passage 1693extends through an extension 1694 and serves as a second flow passagefor the manifold section 1677. The extension 1694 is provided with aconfiguration so that it can be utilized with the quick disconnectfittings 1696 of the type hereinbefore described in FIGS. 12 and 13. Thefitting 1696 is utilized for interconnecting the two sections 1677 and1678. Typically, the manifold section 1677 can be mounted on a frontpanel 1697 and secured thereto by a hexagonal nut 1698. A knob 1699 isprovided which adjusts the position of a needle valve 1701 which can beutilized for controlling the flow of gas through the passage 1686.

The cartridge section 1678 is substantially identical to the cartridgebody 1606 as are the components which are disposed within the body. Theprincipal difference is that the closure for the master diaphragm 1631is provided with a circular member 1706 which takes the place of theflange 1604 provided on the manifold body 1602. This member 1706 isprovided with an extension 1707 which has a conformation which isadapted for use with a quick disconnect 1696 of the type hereinbeforedescribed so that the extension 1694 receives one end of the quickdisconnect connector and the other end receives the extension 1707carried by the member 1706. The member 1706 is held in place by theC-type lock ring 1628. The extension is provided with a bore 1708 whichreceives the extension 1694. The extension 1694 carries an O-ring 1709for forming a gas-tight seal between the extensions 1694 and 1707. Themember 1706 is provided with a passage 1711 in communication with thebore 1708. The passage 1711 serves as a second flow passage for thecartridge section 1678.

Operation and use of the cartridge 1676 in FIGS. 39 and 40 issubstantially identical to that of the cartridge 1601 with the exceptionthat the cartridge 1678 can be separated from the manifold 1677 whendesired merely by pulling the same apart through operation of the quickdisconnect fitting 1696 interconnecting the two. Thus it can be seenthat if it is desired to change the cartridge section 1678, it is merelynecessary to disconnect the tubes which are connected thereto and topull it apart from the manifold section 1677. Similarly, the cartridgesection 1678 can be replaced by sintering it into the quick disconnectfitting 1696 and thereafter connecting the hose or tubing to thecartridge section.

This feature greatly aids interchange of cartridges in that it savesconsiderable time and also expense. It can be seen that such anarrangement particularly facilitates repairs in the field. It alsoshould be appreciated that the fittings provided in each end of thecartridge section 1678 are such that either end of the cartridge can besecured to the quick disconnect fitting 1696 connected to the manifoldsection 1677. This makes it possible to utilize the same cartridgesection 1678 for performing different functions. When the cartridgesection 1678 is mounted in the way shown in FIG. 39, the masterdiaphragm can be servoed through the manifold. By mounting the cartridgesection 1678 in the opposite direction, the master diaphragm can beservoed directly by connecting the outer side of the diaphragm to asource of gas.

In FIG. 41 there is disclosed a cross sectional view of an augmentednebulizer incorporating the present invention and which can be utilizedwith ventilators or respirators of the type herein described. As shownin FIG. 41, the augmented nebulizer has similarities to the nebulizerhereinbefore described in conjunction with FIGS. 20 and 21. Theaugmented nebulizer 1726 shown in FIG. 41 consists of a cup-like memberor container 1727 which is provided with a cylindrical sidewall 1728 anda dished bottom wall 1729. The cup-like member 1727 is adapted to carrya liquid 1730 which is used for forming an aerosol as hereinafterdescribed. The cup-like member 1729 is formed with a depending rim 1731which has its lower extremity lying in a horizontal plane. The dependingrim 1731 is provided with a cutout (not shown) through which a hose orother tubular member (not shown) can extend and be connected to afitting 1733 formed integral with the bottom wall and having a flowpassage 1734 therein extending upwardly into an interior extension 1736formed integral with the bottom wall 1729. The other components interiorof the nebulizer 1726 are very similar to those described in connectionwith those shown in FIGS. 20 and 21.

A cap or cover 1737 is removably mounted on the upper end of thecup-like container and is adapted to close the same. Means is providedfor introducing air into the interior of the container through the capor cover 1737 and consists of a tee 1738 which is formed integral withthe cover 1737. The tee 1738 is provided with inlet ports 1739 which isadapted to be connected to gasses supplied from a volume regulator orfrom the reservoir of the ventilators hereinbefore described. Anotherleg of the tee 1738 is provided with a fitting 1740 which is adapted tobe connected to a counter-pulsing flow of gasses supplied by theventilators of the type hereinbefore described. In this way it can beseen that gases introduced through the port 1739 and through the fitting1740 will be introduced through the other leg of the tee into theinterior of the cup-like member 1727.

An automatic refill float 1741 is positioned within the cup-like member1727 and is utilized to ensure that the liquid 1742 provided in thebottom of the cup-like member 1727 remains at a relatively constantlevel. The liquid is supplied to the cup-like member 1727 through arefill port 1743 carried by the tie 1739. The opening and closing of theport 1743 is controlled by the automatic refill float 1741. A druginjection port 1744 is provided.

The cup-like member 1727 is provided with a large opening or port 1746in the side wall which is in general alignment with the region in thecup-like member in which the liquid is broken up during the nebulizationprocess. A rigid augmentation tube 1747 has one extremity of the samemounted in the port 1746. The augmentation tube 1747 can be constructedof any suitable material. For reasons hereinafter explained, it has beenfound to be desirable to form it of a suitable heat conducting materialsuch as copper. The tube is mounted in the port 1746 in such a manner sothat it can be readily removed. It has a diameter of approximately 3/4of an inch and has a length of approximately six inches. The nebulizeritself has a diameter of approximately one and one half inches. Anannular insert 1748 is provided in the distal extremity of the tube 1747and serves as an anti-spill ring. As indicated in the drawing, the tube1747 can be directly connected to the phasitron hereinbefore described.

Operation and use of the augmented nebulizer 1726 shown in FIG. 41 maynow be described as follows. Let it be assumed that it is desired toventilate a patient which requires additional nebulization. Let it alsobe assumed that the augmented nebulizer 1726 has been properly connectedinto the respiratory circuitry and to the patient. As soon as therespirator is turned on, respiratory gases under pressure ofapproximately 40 psi are delivered into the fitting 1733. This air underpressure is introduced upwardly into the nebulizer and causes a suctionto be created which brings liquid from the bottom of the cup-like member1727 into contact with the air flow through the nebulizer from thereservoir of the volume regulator in one direction and counterpulsingflow from the percussionator in the opposite direction. In order toprevent the particles which are formed during the nebulization processfrom raining out on the side walls of the cup-like container 1727 and inorder to increase the nebulized particles in the gas stream supplied tothe patient, the augmentation tube 1747 is utilized. The augmentationtube 1747 in connection with the cup-like member 1727 forms one end of atee which creates a venturi effect to in effect drop the pressure at theentrance to the tee to entrain additional molecules and particles of theliquid in the gas. In previous embodiments, the use of a counterpulsewas described. In the present embodiment the counterpulsing flow can bedelivered to the nebulizer as shown which can be utilized for providingadditional molecules or particles to be entrained in the gas as itpasses through the augmentation tube.

The augmentation tube 1747 makes the nebulizer appear to have wallswhich are spaced apart by a diameter which is equal to the length of theaugmentation tube plus the original diameter of the nebulizer. It hasbeen found that by providing the tube, the particles of liquid, ratherthan impacting on the side walls of the cup-like member 1727, insteadrush down through the tube as indicated by the arrows 1751 and would becarried down the tube in a venturi-like fashion and be discharged at theend of the tube into the phasitron or other device utilized inconjunction with the augmented nebulizer.

It has been found by the use of the augmentation tube that the outputfrom the augmented nebulizer 1726 can be increased from approximately 60to 160 milliliters an hour using the same operating pressure of 40 psi.

It should be appreciated that if desired still additional augmentationcan be obtained by placing another port in the side wall 180° removedfrom the port 1746 and another augmentation tube placed in that port toagain markedly increase the capacity of the nebulizer in directproportion to the added length of the augmentation tube.

It can be seen that by using one or more augmentation tubes increasednebulization can be obtained while the actual nebulizer can be keptrelatively small in size.

Use of a conductive metal as, for example, copper for the augmentationtube provides several desirable features. For example, it can transferheat into the air stream passing through the tube or transfer heat outof the air stream. It operates as a heat sink in either case. It hasbeen found that there is a 15° temperature drop in the gases passingthrough the augmentation tube because of evaporative cooling within thetube. This is particularly true when oxygen is utilized as the gas.

In many cases it is undesirable to deliver gases to the physiologicalairway of the patient at such a reduced temperature. By utilizing coppertubing, heat is transferred from the ambient atmosphere in the room intothe gases passing through the tube. If it is desired to further heat thegases to ensure that the gases will be delivered at a proper temperatureto the airway of the patient, a heating coil 1754 can be wrapped aroundthe augmentation tube. Electrical energy can be supplied to the heatingcoil 1754 from a conventional 110 volt 60 cycle AC source 1756. Theenergy supplied can be controlled automatically by the use of apotentiometer 1757 controlled by a thermistor 1758 located in a positionclose to the patient airway to sense the gas temperature. In this waythe temperature increase is controlled so that the gas is delivered tothe patient airway at approximately 37° C.

An enhancement circuit for use in the circuitry shown in FIG. 26 isshown in FIG. 52. As shown in FIG. 42, the enhancement circuit involvesthe interruption interval cartridge 1283 that is provided with a valvemember 1286 that is actuated by the diaphragm 1284. The diaphragm 1284is operated from a servo port 1282. The inlet of the interruptioninterval cartridge 1283 is supplied with gas through the oscillatoryCPAP/PEEP needle valve 1351. An adjustable needle valve 1769 is providedas a part of the enhancement circuit shown in FIG. 42 and is connectedbetween the outlet and the inlet of the interruption interval cartridge1283.

As disclosed previously, the ventilator is shown in FIG. 26 prior to themodification which is disclosed in FIG. 42 when the master on/off switch1222 is turned on, gas is supplied through the oscillatory CPAP/PEEPvalve 1351 which meters gas through the normally open interruptioninterval cartridge 1283 and then up through the normally open paralleloscillator cartridge 1321 which is being opened and closed by the timingcircuit hereinbefore described 180° out of phase with or inverse to theopening and closing of the primary oscillator cartridge 1312. Theamplitude or volume flow of the gas to the phasitron 1036 is controlledby the needle valve 1351. The interruption interval cartridge 1283 opensand closes every time the time cycled parallel oscillator cartridge 1321opens and closes. Every time interruption interval cartridge 1283closes, gas cannot flow from the master on-off switch 1222 through theoscillatory C-PAP/PEEP needle valve 1351 which controls the flow to theparallel oscillator cartridge 1321. When this flow is stopped, thecounterpulses hereinbefore described are still provided to the swiveltee 1421 to provide diffusion. Thus there is provided a small amount offlow to the patient coming through the swivel tee 1421. During the timethat flow is interrupted by the interruption interval cartridge 1283,the pressure in the patient airway will be at a base line or at a staticconstant positive airway pressure (CPAP).

The enhancement metering needle valve 1769 which is provided in FIG. 42when added to the circuitry shown in FIG. 26 serves to bypass theinterruption interval cartridge 1283 and supplies gas from theoscillatory CPAP/PEEP needle valve 1351 to the parallel oscillatorcartridge 1331. This causes gas to be delivered to the phasitron 1036.This gas flow is interrupted periodically by the oscillations of theparallel oscillator cartridge 1331 so that there is provided a base lineoscillation of adjustable magnitude as adjusted by the opening of theenhancement metering valve 1769 to provide what can be calledoscillatory demand CPAP or OD CPAP.

In FIGS. 43 and 44 there are shown graphs of two different wave formswhich can be provided with such a ventilator utilizing OD CPAP. In FIG.43 there is shown a wave form 1771 which is provided with oscillatorybase line portions 1771a, and oscillatory rising portions 1771b andfalling portions 1771c. The wave form in FIG. 43 should be compared withthe wave form which is shown in FIG. 33. In FIG. 33 it can be seen thatthere is an ascending portion 1556a in which the pulses increaseprogressively as the lung is inflated until the peak pressure is reachedafter which the lung is deflated through the curve 1556b to a flat baseline portion 1556c. On the other hand, as shown in FIG. 43, by utilizingthe enhancement metering needle valve 1769 hereinbefore described, thereis provided a flat base line portion 1771a, on which there aresuperimposed oscillations or stroke volumes of generally the sameamplitude. On the ascending wave form portion 1771b, the stroke volumesor pulses are at their maximums and these are gradually decreased as thelung is inflated until they reach a minimum after which the lung isdeflated as in the wave form portion 1771c returning to the oscillatorybase line portion 1771a. The rate of decrease of amplitude of theoscillatory pulses or stroke volumes is determined by the rate ofopening of the interrupter cartridge. Thus the faster the opening themore rapidly the amplitude of the stroke volumes decrease. By utilizingsuch decreasing stroke volumes as the lung is inflated, it has beenfound that the hoop stress which is created during use of the ventilatoron the lung is greatly reduced. This is particularly important for usein situations where the patient has a very stiff lung which also oftencan be what is characterized as a "tissue paper" lung which is readilytorn. By utilizing a procedure such as represented by the wave form 1771in which smaller stroke volumes are applied as the lung is inflated,much less hoop stress is generated and therefore there is much lessertendency pneumothoracy. In the wave form 1772 shown in FIG. 44 there isalso provided oscillatory base line portions 1772a, rising portions1772b and falling portions 1772c. However, the wave form has almost asinusoidal characteristic which makes it particularly useful onapplications ranging from neonatal to adult patients. To produce a waveform such as shown in FIG. 44, the flow to the diaphragm 1284 of theinterruption interval cartridge 1283 is controlled so that it opens veryslowly, as for example over a period of approximately 2 seconds. It canbe seen that the slower the interruption interval cartridge opens themore time there is for gas to flow through the enhancement meteringvalve 1769. Therefore it can be seen that the amplitude of theoscillations provided by the enhancement metering valve 1769 graduallyincrease as the opening time for the interruption interval cartridge1283 is increased. As this gradual opening occurs, the base line of thewave form 1772 is gradually raised in a very smooth transition as shownin FIG. 44. The amplitude of the oscillations decreases slightly as thelung is inflated. When the peak inflation is reached, the wave formagain drops down to the base line in the portion 1772c. However, againit can be seen that the drop to the base line is relatively gradual. Byusing such a wave form, it can be seen that a very gentle type ofventilation is provided to the lungs of the patient.

By utilization of the enhancement circuit which is shown in FIG. 42, itcan be seen that it is possible to still utilize CPAP to cause blood toflow from the right side of the heart through the lungs to the left sideof the heart without reducing the cardiac output. This is made possiblebecause oscillations are provided at all times on the wave form duringinhalation and exhalation of the patient. Thus it can be seen that bloodis actually pumped from the right side of the heart to the left side ofthe heart. This provides for vesicular peristalsis in terms of pulmonaryand systemic blood flow as well as enhancing cardiac output duringmechanical ventilation of the lungs of a patient.

It should be appreciated that if it is desired to obtain a wave formwhich is still much more sinusoidal than that which is shown in FIG. 44it is possible to obtain such a wave form by introducing a rampingorifice of a suitable size, as far example, 0.024 inches (not shown) inthe servo port to the interruption interval cartridge 1283. Such aramping orifice allows a more gradual opening and closing of theinterruption interval cartridge 1283 with a net result of causing a slowstart for oscillation as well as a slow oscillatory return to the baseline and thereby providing a much truer sinusoidal pattern when OD-CAPis employed. Significantly, the ramping effect at the start of theoscillation greatly reduces hoop stress within the physiological airwaysfurther minimizing tendencies toward baro-trauma.

In FIG. 45 there is shown a partial schematic view of the primaryoscillator cartridge 1312 which is shown in the ventilator in FIG. 26and the manner in which the loading valve 1337 as been repositioned toachieve stability for the ventilator at different altitudes. In theembodiment shown in FIG. 26 it was found that the gases leaving theloading or check valve 1337 in the position shown in FIG. 26 thatcompression occurring with increasing altitude created turbulence. Thisrequired a more competent check valve with a higher opening pressure toobtain stability which in turn decreased peak oscillatory frequencies.Since this was undesirable, it was found that these deficiencies couldbe overcome by shifting the check valve or loading valve 1337 from whereit was immediately adjacent the outlet 13 to a position at which it isopposite the outlet 1339 or on the opposite side of the needle valve1338. By making this change of position, it has been found that theventilator now produces a remarkably stable pulsation over the entirefrequency range at various altitudes. Turbulence has been eliminated byusing a check valve of the type described in FIGS. 35 and 36.

It should be appreciated that as another embodiment of the ventilatorherein disclosed, the check valve or the loading valve provided on theoutlet of the oscillator cartridge can also be shifted so that it ispositioned after the needle valve in the timing circuit. Thus, forexample, in the ventilator shown in FIG. 18, the check valve 1067 can beshifted into a position so that it immediately follows the outlet 1071from the impact metering cartridge 1069. By making such a rearrangement,there is a more effective timing circuit unloading. The stroke volume atall frequencies is improved. With such a rearrangement it has been foundthat a stable operation can be achieved down to 10 psi operatingpressure.

In FIG. 26 as hereinbefore explained, an accessory pressure regulator1336 is provided which is connected to the phasitron socket 1033. Whenthe predetermined pressure is reached, the socket 1033 is vented toambient. Such pressure limiting means is not particularly effective inlimiting the pressure rise in time cycled pressure variable ventilators.Rather than using a pressure limiting regulator 1366 in the mannerindicated in FIG. 26, it has been found to be preferable with respect totime cycled pressure variable ventilators to use such a device. Thedevice has its output connected to the phasitron socket 1033 and itsinput connected through a one-way valve to the servo port of thenormally open oscillator cartridge 1312. When the relieving pressure ofthe pressure limiting regulator is reached, the gas volume releasedserves to charge the pulsatile timing circuit and thereby causes earlytermination of the timed pulse opening by decreasing the pulse generatorvalve opening time. The tidal volume delivery is limited resulting in aservoed form of peak pressure limiting. In this way it is possible toprovide pressure limiting during the delivery of large tidal volumesunder high peak pressures and/or during ambient density change(altitude) with inspiratory times of over 1.6 seconds without effectingstroke delivery with inspiratory time of under 0.5 seconds. It has beenfound this has been a particularly efficacious way to minimize thetendency of a time-cycled pressure variable ventilator to increase tidalvolume delivery during an ascent to a higher altitude secondary to anincrease in operational pressure.

In FIG. 46, there is disclosed mode switching circuitry which can beutilized with ventilators of the present invention and in particular aventilator of the type described in FIG. 18 which has a capability ofmode selection between intermittent mandatory ventilation andintermittent percussive ventilation, IMV-IPV. The components which areschematically illustrated in FIG. 46 are given the same identificationas they were in the embodiment of the ventilator shown in FIG. 23. Anadditional CPAP isolation check valve 1781 has been provided which is inseries with the demand CPAP cartridge 1174 and the phasitron 1036. Inorder to make two way mode selection possible, a two- way mode selector1782 has been provided. As can be seen, the mode selector 1782 isconnected between the port of the reset cartridge 1044 and the phasitron1036 and alteratively with the IMV timing circuit dump orifice 1184.

The two-way mode selector 1782 makes it possible to select between IPVor IMV functions allowing isolation of demand CPAP during IPV functions.When IPV functions are selected, all demand CPAP functions, whether "on"or "off" are isolated from phasic ventilation. Selection of the IMV modeallows the combined use of phasic ventilation and CPAP/PEEP as long asthe CPAP/PEEP is of less magnitude than the phasic delivery of tidalvolumes.

The penalty for use of the circuit shown in FIG. 46 is minimal. However,there is a slight gas leak from the IMV timing circuit dump orifice 1184which is of 0.018 size during the delivery of either a stroke or tidalvolume. This gas delivery is necessary as entrainment gas during IMVfunctions when demand CPAP/PEEP is not employed. During IPV usage, themandated leak would reduce transport time on a cylinder of gas byapproximately five minutes.

The two-way valve 1184 is connected so that its common port delivers gasto the inlet of the phasitron 1036 with inlet ports selecting either theIMV segment which is downstream of the timing circuit isolation checkvalve 1051 or IMV with timing circuit isolation or IPV by selecting theoutlet flow from the oscillator cartridge 1038 flowing against the IMVtiming circuit dump orifice which dumps to ambient through either thereservoir or the remote switch of the ventilator.

The timing circuit CPAP/PEEP isolation during IMV functions whileemploying the mandated dump orifice with selectable IPV withoutemploying the 0.018 timing circuit dump orifice 1184 is made possible byan alteration of the flow direction through the two-way pneumatic valve1784. This requires the common port of the pneumatic valve to acceptflow from the oscillator cartridge 1038 outlet with selectable deliveryinto either the phasitron inlet port for IPV (without isolation) or theinlet of the 0.018 orifice 1184 to ambient (with isolation) for IMV.Should demand CPAP be selected during IPV isolations with a pressurerise above that programmed for phasic ventilation, the phasicventilation would be muted. Therefore the clinician would not programIMV and demand CPAP as concommitant functions. Such a circuit wouldallow the separate use of either IPV or demand CPAP for weaning. Inaddition there is a maximum conservation of medical gases during IPVfunctions.

Another embodiment of the sleeve check valve or flow obtunder shown inFIG. 19 is shown in FIGS. 35 and 36. This sleeve check valve 1561, whichalso can be called a flow obtunder, consists of a cylindrical body orhousing 1562 which has disposed therein a stem 1563. The cylindricalhousing 1562 is provided with a cylindrical recess 1564 which is incommunication with a passageway 1566 extending through a cylindricalextension 1567. The extension 1567 is provided with circumferential ribs1568 spaced longitudinally of the extension and which are adapted tofrictionally engage flexible tubing of a suitable type such as plastictubing which is pushed onto the extension 1567. The housing 1562 also isprovided with an annular recess 1569 which adjoins a chamfer 1571 makinga graduated transition between the annular recess 1569 and thecylindrical recess 1564.

The stem or body 1563 is provided with a radially extending flange 1572which is adapted to be secured to the cylindrical 1562 by suitable meanssuch as ultrasonic welding. The stem or body 1563 is also provided withcylindrical portions 1573 and 1574 which are adapted to seat within thecylindrical recess 1569 and within the cylindrical recess 1564respectively. The stem or body 1563 is also provided with cylindricallands 1576 and 1577 which are spaced longitudinally away from the flange1572. For reasons hereinafter described, the land 1576 is of a slightlylarger diameter than the land 1577. By way of example, the land 1576 canhave a diameter of 0.215 inches and the land 1577 can have a diameter of0.205 inches. The stem or body 1563 is provided with a radiallyextending lip 1578 on the outer extremity of the same. The stem or body1563 is also provided with a cylindrical extension 1579 on the sideopposite the side the lands 1576 and 1577 are disposed. The extension1579 is provided with spaced apart annular ribs 1581 which are adaptedto be engaged by a flexible hose or tube (not shown) pushed over theextension 1579. The extension 1579 is provided with a flow passage 1582which extends longitudinally of the stem or body 1563 into the region ofthe lands 1576 and 1577. A cross hole 1583 is provided in the stem orbody 1563 between the lands 1576 and 1577 which opens into a pair ofarcuate recesses 1584 and 1586 extending circumferentially of the stemor body 1563. It can be seen that the recesses 1584 and 1586 are of sucha length so that there remain raised portions or ribs 1587 (see FIG. 36)extending between the lands 1576 and 1577. The recesses 1584 and 1586are formed so that the portion of the recess adjacent the land 1576 incross section is in the form of a quarter circle 1584a and that theportion of the recess adjacent the land 1577 is in the form of aninclined plane 1584 which adjoins a vertical surface 1584c. The surface1584c adjoins the circular portion 1584a.

An elastomeric sleeve 1589 is disposed on the stem or body 1563 and isformed of a suitable material such as rubber. It is sized in such amanner so that it makes a relatively tight fit with the land 1576 but isrelatively loose with respect to the land 1577. The sleeve 1589 isprevented from being blown off of the stem or body 1563 by thecircumferential lip or flange 1578 and is therefore captured.

Assuming that a gas is introduced into the passage 1582 from theextension 1579, the gas will flow inwardly of the passage 1582 and willexit through the cross holes 1583. The gas will take the path of leastresistance and will flow over the inclined ramp surface 1584b and thenout circumferentially around the sleeve 1589 and then the land 1577. Gasreleased by the sleeve will then pass out through the passage 1566provided in the cylindrical body 1562. It is has been found that byconstructing the sleeve check valve in this manner, fluttering ordancing of the sleeve 1589 at high frequencies in a range of 1500 to2000 times a minute has been eliminated. This is made possible becausethe sleeve is captured by the land 1576 and is held stationary whileleaving the other end of the sleeve to flex to permit the escape of thegas from the cross holes 1583. In order to prevent flaking off of thedistal extremity of the sleeve 1589, it has been found that it isdesirable to radius the inside distal extremity of the sleeve to providea curved surface 1591. With such a construction it has been found thatthe sleeve check valve 1561 can operate under high frequency conditionsfor long periods of time.

In FIGS. 37 and 38, there is shown a normally open flow/timing cartridge1601 which is particularly useful in the present invention. It consistsof a manifold body 1602 and a cartridge body 1603. The manifold body1602 is generally cylindrical as shown and is provided with a radiallyextending flange 1604 provided on one extremity thereof. The flange 1604is provided with an annular recess 1605.

The manifold body 1602 is provided with three threaded bores 1606, 1607and 1608 disposed circumferentially around the circumference of the body1602 adjacent the drawings, the bores 1606 and 1607 are spaced 180°apart with respect to each other whereas the bore 1608 is disposedbetween the bores 1606 and 1607 and is spaced 90° therefrom. The bores1606 and 1607 are in communication with a flow passage 1609 extendingdiametrically of the body. The flow passage 1609 is in communicationwith a flow passage 1611 which can be identified as a first flow passagefor the manifold body 1602. The flow passage 1611 extends at rightangles to the flow passage 1609 and opens into a threaded bore 1612provided in an externally threaded cylindrical extension 1613 providedon the rear extremity of the body 1602. Another flow passage 1614 isprovided in the body 1602 and is in communication with the threaded bore1612 and is in communication with the bore 1608. Fittings 1616 areprovided in certain of the bores 1606, 1607 and 1608 and are adapted tobe connected to flexible tubes of the type hereinbefore described.

The manifold body 1602 is also provided with another threaded bore 1617extending radially of the body and spaced forwardly of the bores 1606and 1607. It is also provided with a fitting 1616. The bore 1617 is incommunication with a flow passage 1618 extending radially of the boreand is in communication with another flow passage 1619 extendingperpendicular thereto and which opens through the forward extremity ofthe body 1602 into a dish-shaped recess 1621. The flow passage 1619 canbe identified as a second flow passage for the manifold body 1602.

The cartridge body 1603 has a generally bell-shaped configuration. It isprovided with a port or flow passage 1623 on its forward extremity whichis axially aligned with the cartridge body and is in communication witha generally bell-shaped plenum chamber 1624 which opens through the rearof the cartridge body 1603. The flow passage 1623 can be identified as afirst flow passage for the cartridge body 1603. The cartridge body isalso provided with a side port 1626 mounted therein. The ports 1623 and1626 are configured in such a manner so that quick disconnect fittingsof the type hereinbefore described can be utilized in conjunction withthe same.

A poppet valve assembly 1627 is disposed within the bell-shaped chamber1624 and is engaged by the manifold body 1602 which is removably securedto the cartridge body 1603 by suitable means such as a C-type lock ring1628 which engages the rear side of the flange 1604 of the manifold body1602 and an annular inwardly extending lip 1629 provided at the rearextremity of the cartridge body 1603. The poppet valve assembly 1627includes a circular diaphragm 1631 formed of a suitable material such asrubber which has a bead 1632 formed on its outer margin which iscaptured between the manifold body 1602 and the cartridge body 1603. Asshown, this bead 1632 is disposed in the annular recess 1605 of theflange 1604 and seats against a shoulder 1633 of the cartridge body1603. The shoulder 1633 is provided with a raised rounded lip 1634 whichalso serves to capture the bead 1632.

The diaphragm 1631 is provided with a curved semi-circular portion 1636which is relatively thin to permit flexing of the diaphragm. Thediaphragm is also provided with a central circular thicker portion 1637which is of a size so that it is adapted to fit within the dish-shapedrecess 1621 of the manifold body 1602. The central portion 1637 isprovided with a plurality, in this case, four cylindrical projections orfeet 1638 which are uniformly spaced on the surface of the centralportion 1637. The underside of the diaphragm 1631 is in communicationwith a flow passage 1619 of the manifold body 1602. At least a portionof the flow passage 1619 can be considered to be a second flow passagefor the cartridge body 1603.

The central portion 1637 is also provided with a centrally disposedcylindrical protrusion 1639 on the side opposite on which theprojections or feet 1638 are disposed. The centrally disposed protrusion1639 serves as a seat for a cam button 1641 of a suitable material suchas plastic. The cam button is provided with a recess 1642 which receivesthe protrusion 1639. It is also provided with a radially extendingflange 1643 which terminates short of the semicircular portion 1636 ofthe diaphragm 1631. The cam button 1641 extends through a ring or washer1644 formed of a suitable non-corrosive metal such as brass or stainlesssteel. The forward extremity of the cam button engages a diaphragm seal1646 formed of a suitable material such as rubber. The seal 1646 isprovided with an outer annular bead 1647 which is captured between thewasher 1644 and a shoulder 1648. The washer 1644 is held in place by aC-type lock ring 1649 which engages an annular recess 1650 provided inthe cartridge body 1603.

An elastomeric percussion pad 1651 is disposed in the ring 1644 betweenthe seal 1646 and the top of the cam button 1641 and has a diameterslightly greater than that of the cam button. This pad can be loadedwith 15 to 20% graphite so as to provide a slippery permanent shockabsorbing and compression absorbing interface between the cam button 641and the disc 1646. Thus, the bottom surface of the seal 1646 isprotected from abrasion by compression and stretching of the seal bymovement of the cam button 1641.

A poppet or poppet valve plunger 1652 is provided which is seated overthe disc 1646. The valve plunger or poppet 1652 is made of a suitablematerial such as a relatively hard plastic and is provided with a stem1653. The stem 1653 is generally cylindrical in form and extends atright angles or forwardly from a radially extending flange or poppethead 1654. The flange 1654 is provided with a circular recess 1656facing rearwardly and which has disposed therein a pad 1657. The pad1657 is formed of a suitable elastomeric with a 15 to 20% loading ofgraphite.

The pad 1657 has a diameter greater than that of the cam button 1641 andserves to protect the seal 1646 from abrasion caused by compression andstretching of the diaphragm seal between the poppet head 1654 and thecam button 1641.

The valve plunger 1652 is provided with an annular recess 1658 on theupper extremity of the stem 1653 and has mounted therein an O-ring 1659.The O-ring 1659 is adapted to form a sealing engagement with an annularinclined valve seating surface 1661. Compression of the O-ring islimited by limiting the travel of the plunger 1652. The plunger 1652cannot travel beyond the point where the head 1654 strikes the shoulder1662. A pilot bore or chamber 1663 adjoins the valve seating surface1661 and the plenum chamber 1624.

In the event that the diaphragm seal 1646 is breached, vent holes 1664to ambient in the cartridge body 1603 are sufficient to limit thepressure rise caused by on-servoing against the forward side of themaster diaphragm 1631. These vent holes 1664 are sufficiently large toassure there is sufficient venting to negate any possible hightemperature stall as the diaphragm becomes more pliant at hightemperatures as well as potential hard open servoing.

The cartridge 1601 is provided with a needle valve assembly 1666 whichis threaded into the bore 1612. It is provided with a control knob 1667for adjusting the position of a needle valve 1668 to control the flow ofgas from the passage 1611. The cartridge 1601 can be supported in asuitable manner such as by mounting it on a panel 1669 and securing itthereto by a nut 1671 as shown in FIG. 37.

Operation and use of the normally open flow/timing cartridge 1601 shownin FIGS. 37 and 38 may now be briefly described as follows. Let it beassumed that the cartridge 1601 is in its normally open position. Inthis position gas may flow from the port 1626 to the port 1623 or viceversa. Let it now be assumed that it is desired to interrupt this flowof gas from the port 1626 to the port 1623. This is accomplished byapplying gas under pressure to the servo port 1617. This gas passesthrough the passages 1618 and 1619 to the underside of the diaphragm1631 to cause it to rapidly move the poppet valve in the form of theO-ring 1659 into rapid engagement with the seat 1661 to prevent furtherflow of gases from the port 1626 to the port 1623.

Now let it be assumed that it is desired to move the cartridge 1601 fromthe closed position to its normally open position. To accomplish this,the pressure from behind the diaphragm 1631 is bled down gradually. Assoon as there has been some bleed down, the poppet valve 1652 will havea tendency to open at least a slight amount. This permits the pressureof the gas which is in the port 1623 to act upon the very small area ofthe end of the poppet valve 1652, as for example, approximately onequarter of an inch in diameter and to act upon the diaphragm 1631 whichbecause of its much larger area would cause the poppet valve to snaprapidly to a completely open position. Conversely when pressure isapplied to the servo port 1606, the poppet valve 1652 is cammed rapidlyinto a closed position. This snap opening and closing of the poppetvalve 1652 is created because of the large differential between thequarter of an inch diameter surface represented by the O-ring 1659 atthe top of the poppet valve and the one-half inch diameter surface ofthe diaphragm. In other words by providing this large differential it ispossible to obtain almost instantaneous opening and closing of thepoppet valve. This rapid opening and closing makes possible very highfrequency of operation of the cartridge.

The cartridge 1601 will work over a very wide range of operationalpressures because the same operational pressure is used in the inletport 1623 as in the servo port 1617. Thus, for example, it is possibleto operate this type of cartridge with pressures ranging from 2 topounds to 100 pounds per square inch. As hereinafter explained, it isthis capability of the cartridge which makes it possible to operate downto the neonatal range and up to an adult range and also makes itpossible to provide a respirator which has a single control.

There are a number of features in the construction of the cartridge 1601which makes this long life possible. As pointed out above, the poppet orvalve plunger 1652 has been provided with an insert pad 1657 which isprovided with graphite. This pad has a diameter which is slightlygreater than that of the compression of the cam button. There istherefore provided a slippery permanent shock and compression absorbinginterface between the cam button 1641 and the valve plunger 1652. Thisshock and compression absorbing interface also minimizes abrasion causedby compression and stretching of the diaphragm.

From the construction shown it can be seen that the poppet 1652 residesin a cylindrical chamber with a pilot bore 1663 rising from the inclinedvalve seat 1661. The pilot bore above the valve seat provides acentering effect for alignment purposes as the poppet stem 1653 carryingthe O-ring 1659 moves towards the closed position. Gas flowing into theinlet port 1623 passes around the O-ring and causes centering alignmentof the poppet assembly. Flow against the O-ring provides an openingpiston effect against the poppet carrying the O-ring. The outlet port1626 is disposed so that the gases exit around the stem and also causethe stem to be held in alignment within the conical valve seat limits.

This arrangement of the poppet assembly inhibits erratic functioning ofthe poppet valve. Adequate clearance is provided between the O-ring 1659and the valve seat 1661. A definitive pressure drop across the O-ring1659 which serves as a valve gate is maintained during all flowconditions to maintain full flutter-free opening as well as an openingservoing force. These requirements are satisfied by the cylindrical bore1663 rising from the valve seat 1661 which is inclined at a 45° anglewith sufficient height to accommodate the full stroke with a diameterthat allows maximum flow while centering the poppet stem carrying theO-ring within the conical seat area. The differential diameter betweenthe O-ring gate valve and the diaphragm seal is at least 1 to 2 causinga pressure buildup in the poppet cylinder at the point of opening toback servo the diaphragm seal to allow the poppet to ride against theascending diaphragm dome. Lateral movement of the O-ring gate is limitedby the pilot bore 1663 thereby capturing the valve gate so that itremains in alignment during its stroke.

The amount of O-ring compression has been limited. When the closingservoing pressures exceed 25 psi (which is beyond the normal operatingpressure range) the poppet head 1654 reaches the shoulder 1662 whichlimits further forward travel and further O-ring compression. The travelof the servoing master diaphragm 1631 is limited by progressivediaphragmatic unloading as the semi-circular portion or convolution isflexed. This flexing is limited by the geometry of the bell-shapedchamber 1624.

The present design utilizing the elastomeric graphite filled pads 1651and 1657 permits the use of a thin low durometer diaphragm seal 1646 torapidly respond to both mechanical opening and closing pressures undervarious working conditions while still providing the necessaryresistance to abrasion so as to provide a long working life. By keepingthe poppet 1652 centered, the friction between the poppet head rim andthe walls of the chamber are minimized. The cartridge 1601 makespossible the delivering of pulsatile stroke volumes at a selectedopening and closing ratio and time as inlet pressures are increased.

From the arrangement hereinbefore described it can be seen that thepoppet 1652 is cellularized in its chamber by a captured diaphragm seal1646 which in turn is actuated downward by a cam button 1641 under thecontrol of the master servoing diaphragm 1631. While closing ismechanical in nature, opening is caused by a pressure rise in the plenumchamber 1624 acting to cause a yield of all components of elastomericclosing. Piston effects acting upon differential servoing areas balanceoperations between servoing and valving actions as operational pressuresare changed. The flight path of the poppet valve gate captured on thepoppet assembly is precisely guided within its valve seat cone by thepilot bore 1663 above the valve seat.

By constructing the cartridge 1601 in the manner hereinbefore described,it has been found that diaphragm seal life has been greatly prolonged.The cartridge can operate at high frequencies with very little noise.Peak flow restrictions are overcome and stalling is inhibited. Pressuresranging from 15 to 100 psi are readily accommodated. Cyclic operationfrom 1 to 1800 cycles per minute could be readily clearance of thepoppet valve is provided to permit back servoing in proportion tooutflow within a flow range from 5 to 200 liters per minute. Valveopening and closing is substantially instantaneous to provide maximumflow during the valve open interval. It has been found to be capable ofoperating for prolonged periods of time at high frequency oscillationwithout self destructing. Billions of cycles of operation can beperformed before overhaul is required.

Another embodiment of the normally open flow/timing cartridge is shownin FIGS. 39 and 40. As shown therein, the cartridge 1676 consists of amanifold section 1677 and a cartridge section 1678 both of whichcombined perform the same function as the cartridge 1601. The manifoldsection 1677 is provided with a cylindrical manifold body 1679 providedwith three threaded bores 1681, 1682 and 1683 which are arranged in thesame manner as the bores 1606, 1607 and 1608 in the manifold body 1602.They are connected by passages 1684, 1686 and 1687 in the same way thatpassages 1609, 1611 and 1614 interconnect the bores 1606, 1607 and 1608.The passage 1686 serves as the first passage for the manifold section1677. In a similar manner, the manifold body 1679 is provided with athreaded bore 1688 which extends into an exteriorly threaded protrusion1689. The bore 1688 is in communication with the passages 1686 and 1687.The manifold body 1679 is also provided with another threaded bore 1691which is offset longitudinally as well as circumferentially of the bores1681, 1682 and 1683. The bore 1691 is in communication with a flowpassage 1692 which extends at right angles to another flow passage 1693extending axially of the manifold body 1679. The flow passage 1693extends through an extension 1694 and serves as a second flow passagefor the manifold section 1677. The extension 1694 is provided with aconfiguration so that it can be utilized with the quick disconnectfittings 1696 of the type hereinbefore described in FIGS. 12 and 13. Thefitting 1696 is utilized for interconnecting the two sections 1677 and1678. Typically, the manifold section 1677 can be mounted on a frontpanel 1697 and secured thereto by a hexagonal nut 1698. A knob 1699 isprovided which adjusts the position of a needle valve 1701 which can beutilized for controlling the flow of gas through the passage 1686.

The cartridge section 1678 is substantially identical to the cartridgebody 1606 as are the components which are disposed within the body. Theprincipal difference is that the closure for the master diaphragm 1631is provided with a circular member 1706 which takes the place of theflange 1604 provided on the manifold body 1602. This member 1706 isprovided with an extension 1707 which has a conformation which isadapted for use with a quick disconnect 1696 of the type hereinbeforedescribed so that the extension 1694 receives one end of the quickdisconnect connector and the other end receives the extension 1707carried by the member 1706. The member 1706 is held in place by theC-type lock ring 1628. The extension is provided with a bore 1708 whichreceives the extension 1694. The extension 1695 carries an O-ring 1709for forming a gas-tight seal between the extensions 1694 and 1707. Themember 1706 is provided with a passage 1711 in communication with thebore 1708. The passage 1711 serves as a second flow passage for thecartridge section 1678.

Operation and use of the cartridge 1676 in FIGS. 39 and 40 issubstantially identical to that of the cartridge 1601 with the exceptionthat the cartridge 1678 can be separated from the manifold 1677 whendesired merely by pulling the same apart through operation of the quickdisconnect fitting 1696 interconnecting the two. Thus it can be seenthat if it is desired to change the cartridge section 1678, it is merelynecessary to disconnect the tubes which are connected thereto and topull it apart from the manifold section 1677. Similarly, the cartridgesection 1678 can be replaced by inserting it into the quick disconnectfitting 1696 and thereafter connecting the hose or tubing to thecartridge section.

This feature greatly aids interchange of cartridges in that it savesconsiderable time and also expense. It can be seen that such anarrangement particularly facilitates repairs in the field. It alsoshould be appreciated that the fittings provided in each end of thecartridge section 1678 are such that either end of the cartridge can besecured to the quick disconnect fitting 1696 connected to the manifoldsection 1677. This makes it possible to utilize the same cartridgesection 1678 for performing different functions. When the cartridgesection 1678 is mounted in the way shown in FIG. 39, the masterdiaphragm can be servoed through the manifold. By mounting the cartridgesection 1678 in the opposite direction, the master diaphragm can beservoed directly by connecting the outer side of the diaphragm to asource of gas.

In FIG. 41 there is disclosed a cross sectional view of an augmentednebulizer incorporating the present invention and which can be utilizedwith ventilators or respirators of the type herein described. As shownin FIG. 41, the augmented nebulizer has similarities to the nebulizerhereinbefore described in conjunction with FIGS. 20 and 21. Theaugmented nebulizer 1726 shown in FIG. 41 consists of a cup-like memberor container 1727 which is provided with a cylindrical sidewall 1728 anda dished bottom wall 1729. The cup-like member 1727 is adapted to carrya liquid 1730 which is used for forming an aerosol as hereinafterdescribed. The cup-like member 1729 is formed with a depending rim 1731which has its lower extremity lying in a horizontal plane. The dependingrim 1731 is provided with a cutout (not shown) through which a hose orother tubular member (not shown) can extend and be connected to afitting 1733 formed integral with the bottom wall and having a flowpassage 1734 therein extending upwardly into an interior extension 1736formed integral with the bottom wall 1729. The other components interiorof the nebulizer 1726 are very similar to those described in connectionwith those shown in FIGS. 20 and 21.

A cap or cover 1737 is removably mounted on the upper end of thecup-like container and is adapted to close the same. Means is providedfor introducing air into the interior of the container through the capor cover 1737 and consists of a tee 1738 which is formed integral withthe cover 1737. The tee 1738 is provided with inlet ports 1739 which isadapted to be connected to gasses supplied from a volume regulator orfrom the reservoir of the ventilators hereinbefore described. Anotherleg of the tee 1738 is provided with a fitting 1740 which is adapted tobe connected to a counter-pulsing flow of gasses supplied by theventilators of the type hereinbefore described. In this way it can beseen that gases introduced through the port 1739 and through the fitting1740 will be introduced through the other leg of the tee into theinterior of the cup-like member 1727.

An automatic refill float 1741 is positioned within the cup-like member1727 and is utilized to ensure that the liquid 1742 provided in thebottom of the cup-like member 1727 remains at a relatively constantlevel. The liquid is supplied to the cup-like member 1727 through arefill port 1743 carried by the tie 1739. The opening and closing of theport 1743 is controlled by the automatic refill float 1741. A druginjection port 1744 is provided.

The cup-like member 1727 is provided with a large opening or port 1746in the side wall which is in general alignment with the region in thecup-like member in which the liquid is broken up during the nebulizationprocess. A rigid augmentation tube 1747 has one extremity of the samemounted in the port 1746. The augmentation tube 1747 can be constructedof any suitable material. For reasons hereinafter explained, it has beenfound to be desirable to form it of a suitable heat conducting materialsuch as copper. The tube is mounted in the port 1746 in such a manner sothat it can be readily removed. It has a diameter of approximately 3/4of an inch and has a length of approximately six inches. The nebulizeritself has a diameter of approximately one and one half inches. Anannular insert 1748 is provided in the distal extremity of the tube 1747and serves as an anti-spill ring. As indicated in the drawing, the tube1747 can be directly connected to the phasitron hereinbefore described.

Operation and use of the augmented nebulizer 1726 shown in FIG. 41 maynow be described as follows. Let it be assumed that it is desired toventilate a patient which requires additional nebulization. Let it alsobe assumed that the augmented nebulizer 1726 has been properly connectedinto the respiratory circuitry and to the patient. As soon as therespirator is turned on, respiratory gases under pressure ofapproximately 40 psi are delivered into the fitting 1733. This air underpressure is introduced upwardly into the nebulizer and causes a suctionto be created which brings liquid from the bottom of the cup-like member1727 into contact with the air flow through the nebulizer from thereservoir of the volume regulator in one direction and counterpulsingflow from the percussionator in the opposite direction. In order toprevent the particles which are formed during the nebulization processfrom raining out on the side walls of the cup-like container 1727 and inorder to increase the nebulized particles in the gas stream supplied tothe patient, the augmentation tube 1747 is utilized. The augmentationtube 1747 in connection with the cup-like member 1727 forms one end of atee which creates a venturi effect to in effect drop the pressure at theentrance to the tee to entrain additional molecules and particles of theliquid in the gas. In previous embodiments, the use of a counterpulsewas described. In the present embodiment the counterpulsing flow can bedelivered to the nebulizer as shown which can be utilized for providingadditional molecules or particles to be entrained in the gas as itpasses through the augmentation tube.

The augmentation tube 1747 makes the nebulizer appear to have wallswhich are spaced apart by a diameter which is equal to the length of theaugmentation tube plus the original diameter of the nebulizer. It hasbeen found that by providing the tube, the particles of liquid, ratherthan impacting on the side walls of the cup-like member 1727, insteadrush down through the tube as indicated by the arrows 1751 and would becarried down the tube in a venturi-like fashion and be discharged at theend of the tube into the phasitron or other device utilized inconjunction with the augmented nebulizer. It has been found by the useof the augmentation tube that the output from the augmented nebulizer1726 can be increased from approximately 60 to 160 milliliters an hourusing the same operating pressure of 40 psi.

It should be appreciated that if desired still additional augmentationcan be obtained by placing another port in the side wall 180° removedfrom the port 1746 and another augmentation tube placed in that port toagain markedly increase the capacity of the nebulizer in directproportion to the added length of the augmentation tube.

It can be seen that by using one or more augmentation tubes increasednebulization can be obtained while the actual nebulizer can be keptrelatively small in size.

Use of a conductive metal as, for example, copper for the augmentationtube provides several desirable features. For example, it can transferheat into the air stream passing through the tube or transfer heat outof the air stream. It operates as a heat sink in either case. It hasbeen found that there is a 15° temperature drop in the gases passingthrough the augmentation tube because of evaporative cooling within thetube. This is particularly true when oxygen is utilized as the gas.

In many cases it is undesirable to deliver gases to the physiologicalairway of the patient at such a reduced temperature. By utilizing coppertubing, heat is transferred from the ambient atmosphere in the room intothe gases passing through the tube. If it is desired to further heat thegases to ensure that the gases will be delivered at a proper temperatureto the airway of the patient, a heating coil 1754 can be wrapped aroundthe augmentation tube. Electrical energy can be supplied to the heatingcoil 1754 from a conventional 110 volt 60 cycle AC source 1756. Theenergy supplied can be controlled automatically by the use of apotentiometer 1757 controlled by a thermistor 1758 located in a positionclose to the patient airway to sense the gas temperature. In this waythe temperature increase is controlled so that the gas is delivered tothe patient airway at approximately 37° C. An enhancement circuit foruse in the circuitry shown in FIG. 26 is shown in FIG. 42. As shown inFIG. 42, the enhancement circuit involves the interruption intervalcartridge 1283 that is provided with a valve member 1286 that isactuated by the diaphragm 1284. The diaphragm 1284 is operated from aservo port 1282. The inlet of the interruption interval cartridge 1283is supplied with gas through the oscillator CPAP/PEEP needle valve 1351.An adjustable needle valve 1769 is provided as a part of the enhancementcircuit shown in FIG. 42 and is connected between the outlet and theinlet of the interruption interval cartridge 1283.

As disclosed previously, the ventilator is shown in FIG. 26 prior to themodification which is disclosed in FIG. 42 when the master on/off switch1222 is turned on, gas is supplied through the oscillatory CPAP/PEEPvalve 1351 which meters gas through the normally open interruptioninterval cartridge 1283 and then up through the normally open paralleloscillator cartridge 1321 which is being opened and closed by the timingcircuit hereinbefore described 180° out of phase with or inverse to theopening and closing of the primary oscillator cartridge 1312. Theamplitude or volume flow of the gas to the phasitron 1036 is controlledby the needle valve 1351. The interruption interval cartridge 1283 opensand closes every time the time cycled parallel oscillator cartridge 1321opens and closes. Every time interruption interval cartridge 1283closes, gas cannot flow from the master on-off switch 1222 through theoscillatory C-PAP/PEEP needle valve 1351 which controls the flow to theparallel oscillator cartridge 1321. When this flow is stopped, thecounterpulse hereinbefore described are still provided to the swivel tee1421 to provide diffusion. Thus there is provided a small amount of flowto the patient coming through the swivel tee 1421. During the time thatflow is interrupted by the interruption interval cartridge 1283, thepressure in the patient airway will be at a base line or at a staticconstant positive airway pressure (CPAP).

The enhancement metering needle valve 1769 which is provided in FIG. 42when added to the circuitry shown in FIG. 26 serves to bypass theinterruption interval cartridge 1283 and supplies gas from theoscillatory CPAP/PEEP needle valve 1351 to the parallel oscillatorcartridge 1331. This causes gas to be delivered to the phasitron 1036.This gas flow is interrupted periodically by the oscillations of theparallel oscillator cartridge 1331 so that there is provided a base lineoscillation of adjustable magnitude as adjusted by the opening of theenhancement metering valve 1769 to provide what can be calledoscillatory demand CPAP or OD CPAP.

In FIGS. 43 and 44 there are shown graphs of two different wave formswhich can be provided with such a ventilator utilizing OD CPAP. In FIG.43 there is shown a wave form 1771 which is provided with oscillatorybase line portions 1771a, and oscillatory rising portions 1771b andfalling portions 1771c. The wave form in FIG. 43 should be compared withthe wave form which is shown in FIG. 33. In FIG. 33 it can be seen thatthere is an ascending portion 1556a in which the pulses increaseprogressively as the lung is inflated until the peak pressure is reachedafter which the lung is deflated through the curve 1556b to a flat baseline portion 1556c. On the other hand, as shown in FIG. 43, by utilizingthe enhancement metering needle valve 1769 hereinbefore described, thereis provided a flat base line portion 1771a, on which there aresuperimposed oscillations or stroke volumes of generally the sameamplitude. On the ascending wave form portion 1771b, the stroke volumesor pulses are at their maximums and these are gradually decreased as thelung is inflated until they reach a minimum after which the lung isdeflated as in the wave form portion 1771c returning to the oscillatorybase line portion 1771a. The rate of decrease of amplitude of theoscillatory pulses or stroke volumes is determined by the rate ofopening of the interrupter cartridge. Thus the faster the opening themore rapidly the amplitude of the stroke volumes decrease. By utilizingsuch decreasing stroke volumes as the lung is inflated, it has beenfound that the hoop stress which is created during use of the ventilatoron the lung is greatly reduced. This is particularly important for usein situations where the patient has a very stiff lung which also oftencan be what is characterized as a "tissue paper" lung which is readilytorn. By utilizing a procedure such as represented by the wave form 1771in which smaller stroke volumes are applied as the lung is inflated,much less hoop stress is generated and therefore there is much lessertendency of pneumothoracy.

In the wave form 1772 shown in FIG. 44 there is also providedoscillatory base line portions 1772a, rising portions 1772b and fallingportions 1772c. However, the wave form has almost a sinusoidalcharacteristic which makes it particularly useful on applicationsranging from neonatal to adult patients. To produce a wave form such asshown in FIG. 44, the flow to the diaphragm 1284 of the interruptioninterval cartridge 1283 is controlled so that it opens very slowly, asfor example, over a period of approximately 2 seconds. It can be seenthat the slower the interruption interval cartridge opens the more timethere is for gas to flow through the enhancement metering valve 1769.Therefore it can be seen that the amplitude of the oscillations providedby the enhancement metering valve 1769 gradually increase as the openingtime for the interruption interval cartridge 1283 is increased. As thisgradual opening occurs, the base line of the wave form 1772 is graduallyraised in a very smooth transition as shown in FIG. 44. The amplitude ofthe oscillations decreases slightly as the lung is inflated. When thepeak inflation is reached, the wave form again drops down to the baseline in the portion 1772c. However, again it can be seen that the dropto the base line is relatively gradual. By using such a wave form, itcan be seen that a very gentle type of ventilation is provided to thelungs of the patient.

By utilization of the enhancement circuit which is shown in FIG. 42, itcan be seen that it is possible to still utilize CPAP to cause blood toflow from the right side of the heart through the lungs to the left sideof the heart without reducing the cardiac output. This is made possiblebecause oscillations are provided at all times on the wave form duringinhalation and exhalation of the patient. Thus it can be seen that bloodis actually pumped from the right side of the heart to the left side ofthe heart. This provides for vesicular peristalsis in terms of pulmonaryand systemic blood flow as well as enhancing cardiac output duringmechanical ventilation of the lungs of a patient.

It should be appreciated that if it is desired to obtain a wave formwhich is still much more sinusoidal than that which is shown in FIG. 44it is possible to obtain such a wave form by introducing a rampingorifice of a suitable size, as for example, 0.024 inches (not shown) inthe servo port to the interruption interval cartridge 1283. Such aramping orifice allows a more gradual opening and closing of theinterruption interval cartridge 1283 with a net result of causing a slowstart for oscillation as well as a slow oscillator return to the baseline and thereby providing a much truer sinusoidal pattern when OD-CAPis employed. Significantly, the ramping effect at the start of theoscillation greatly reduces hoop stress within the physiological airwaysfurther minimizing tendencies toward baro-trauma.

In FIG. 45 there is shown a partial schematic view of the primaryoscillator cartridge 1312 which is shown in the ventilator in FIG. 26and the manner in which the loading valve 1337 as been repositioned toachieve stability for the ventilator at different altitudes. In theembodiment shown in FIG. 26 it was found that the gases leaving theloading or check valve 1337 in the position shown in FIG. 26 thatcompression occurring with increasing altitude created turbulence. Thisrequired a more competent check valve with a higher opening pressure toobtain stability which in turn decreased peak oscillatory frequencies.Since this was undesirable, it was found that these deficiencies couldbe overcome by shifting the check valve or loading valve 1337 from whereit was immediately adjacent the outlet 13 to a position at which it isopposite the outlet 1339 or on the opposite side of the needle valve1338. By making this change of position, it has been found that theventilator now produces a remarkably stable pulsation over the entirefrequency range at various altitudes. Turbulence has been eliminated byusing a check valve of the type described in FIGS. 35 and 36.

It should be appreciated that as another embodiment of the ventilatorherein disclosed, the check valve or the loading valve provided on theoutlet of the oscillator cartridge can also be shifted so that it ispositioned after the needle valve in the timing circuit. Thus, forexample, in the ventilator shown in FIG. 18, the check valve 1067 can beshifted into a position so that it immediately follows the outlet 1071from the impact metering cartridge 1069. By making such a rearrangement,there is a more effective timing circuit unloading. The stroke volume atall frequencies is improved. With such a rearrangement it has been foundthat a stable operation can be achieved down to 10 psi operatingpressure.

In FIG. 26 as hereinbefore explained, an accessory pressure limitingregulator 1336 is provided which is connected to the phasitron socket1033. When the predetermined pressure is reached, the socket 1033 isvented to ambient. Such pressure limiting means is not particularlyeffective in limiting the pressure rise in time cycled pressure variableventilators. Rather than using a pressure limiting regulator 1366 in themanner indicated in FIG. 26, it has been found to be preferable withrespect to time cycled pressure variable ventilators to use such adevice. The device has its output connected to the phasitron socket 1033and its input connected through a one-way valve to the servo port of thenormally open oscillator cartridge 1312. When the relieving pressure ofthe pressure limiting regulator is reached, the gas volume releasedserves to charge the pulsatile timing circuit and thereby causes earlytermination of the timed pulse opening by decreasing the pulse generatorvalve opening time. The tidal volume delivery is limited resulting in aservoed form of peak pressure limiting. In this way it is possible toprovide pressure limiting during the delivery of large tidal volumesunder high peak pressures and/or during ambient density change(altitude) with inspiratory times of over 1.5 seconds without effectingstroke delivery with inspiratory time of under 0.5 seconds. It has beenfound this has been a particularly efficacious way to minimize thetendency of a time-cycled pressure variable ventilator to increase tidalvolume delivery during an ascent to a higher altitude secondary to anincrease in operational pressure.

In FIG. 46, there is disclosed mode switching circuitry which can beutilised with ventilators of the present invention and in particular aventilator of the type described in FIG. 18 which has a capability ofmode selection between intermittent mandatory ventilation andintermittent percussive ventilation, IMV-IPV. The components which areschematically illustrated in FIG. 46 are given the same identificationas they were in the embodiment of the ventilator shown in FIG. 23. Anadditional CPAP isolation check valve 1781 has been provided which is inseries with the demand CPAP cartridge 1174 and the phasitron 1036. Inorder to make two way mode selection possible, a two- way mode selector1782 has been provided. As can be seen, the mode selector 1782 isconnected between the port of the reset cartridge 1044 and the phasitron1036 and alternatively with the IMV timing circuit dump orifice 1184.

The two-way mode selector 1782 makes it possible to select between IPVor IMV functions allowing isolation of demand CPAP during IPV functions.When IPV functions are selected, all demand CPAP functions, whether "on"or "off" are isolated from phasic ventilation. Selection of the IMV modeallows the combined use of phasic ventilation and CPAP/PEEP as long asthe CPAP/PEEP is of less magnitude than the phasic delivery of tidalvolumes.

The penalty for use of the circuit shown in FIG. 46 is minimal. However,there is a slight gas leak from the IMV timing circuit dump orifice 1184which is of 0.018 size during the delivery of either a stroke or tidalvolume. This gas delivery is necessary as entrainment gas during IMVfunctions when demand CPAP/PEEP is not employed. During IPV usage, themandated leak would reduce transport time on a cylinder of gas byapproximately five minutes.

The two-way valve 1184 is connected so that its common port delivers gasto the inlet of the phasitron 1036 with inlet ports selecting either theIMV segment which is downstream of the timing circuit isolation checkvalve 1051 or IMV with timing circuit isolation or IPV by selecting theoutlet flow from the oscillator cartridge 1038 flowing against the IMVtiming circuit dump orifice which dumps to ambient through either thereservoir or the remote switch of the ventilator.

The timing circuit CPAP/PEEP isolation during IMV functions whileemploying the mandated dump orifice with selectable IPV withoutemploying the 0.018 timing circuit dump orifice 1184 is made possible byan alteration of the flow direction through the two-way pneumatic valve1784. This requires the common port of the pneumatic valve to acceptflow from the oscillator cartridge 1038 outlet with selectable deliveryinto either the phasitron inlet port for IPV (without isolation) or theinlet of the 0.018 orifice 1184 to ambient (with isolation) for IMV.Should demand CPAP be selected during IPV isolations with a pressurerise above that programmed for phasic ventilation, the phasicventilation would be muted. Therefore the clinician would not programIMV and demand CPAP as concommitant functions. Such a circuit wouldallow the separate use of either IPV or demand CPAP for weaning. Inaddition there is a maximum conservation of medical gases during IPVfunctions.

From the foregoing it can be seen that there have been provided a numberof embodiments of ventilators incorporating the present inventionutilizing oscillators which have produce pulsatile gases which aresupplied to the airway of the patient and which can be impressed upon aconstant positive airway pressure. The pulsatile gases can be suppliedunder manual control to the patient airway or alternatively can besupplied with automatic timing or phasing. In addition, tidal volumescan be manually or automatically superimposed upon the pulsatile gasessupplied to the patient or alternatively pulsatile gases can beinterrupted during the time that the tidal volumes are being deliveredto the airway of the patient. Particularly novel oscillator circuits areprovided for delivering the pulsatile gases to the airway of thepatient. In addition, a particularly novel nebulizer has been providedfor use in the breathing circuit. Also, a particularly novel venturi jetand exhalation valve assembly has been provided which makes possiblehigh frequency phase oscillation. The oscillators are constructed inmodular form so that ventilators having various capabilities can beprovided with a minimum amount of changes. The ventilators of thepresent invention make it possible to supply percussive pulsatile gasesto the physiological and cardiopulmonary structures of the patient tomaintain maximum blood/gas interface and cardiac output while mobilizingintrasecretions with minimal tendency toward pulmonary barotrauma. Thepulsatile gases can be supplied to the airway of the patient with aprogrammable amplitude to produce the desired intrapulmonary mechanicalmixing in the patient airway. At least certain of the ventilators of thepresent invention can be operated to meet the lung size requirements ofthe mammalian patient by increasing or decreasing source pressures asfor example 25 psi for neonates, 35 psi for pediatrics and 50 psi foradults. As the source of pressure is reduced, the frequency range isincreased thereby maintaining optimal clinical parameters of bothfrequency and pressure rise for the mammal being treated. Alarm andfailsafe functions are provided in the ventilators in the event thatprogrammed mean airway pressures are exceeded. In the event of explosivedecompression, oxygen enrichment is provided while at the same timeproviding venting to the atmosphere and maintaining a constant positiveairway pressure for the patient.

In addition, from the foregoing, it can be seen that there has beenprovided a ventilator which makes possible volumetric diffusionrespiration, oscillatory demand CPAP, intermittent percussiveventilation and routine ventilatory procedures along with mechanicalassist/control and spontaneous respiratory combinations in all mammalianlungs. The particular exhalation valve assembly utilized makes itpossible to work with gas pressure substantially below the conventional50 psi required as, for example, as low as 20 psi.

Also, from the foregoing it can be seen that there has been provided aventilator in FIGS. 25 through 31 which has many desirable features. Itis possible to provide ventilation ranging all the way from neonates togiants. Control is provided over inspiratory time, expiratory time,inspiratory flow rate, demand CPAP/PEEP and aerosal generation. Negativeand positive IE ratios can be programmed. Inspiratory times can rangefrom 0.03 to 3 seconds with expiratory times ranging from 0.3 to off.Inspiratory flow rates can be varied from off to 100 liters per minuteto ambient. Demand CPAP/PEEP can be selected from off to 30 centimetersof H₂ O with programming to 60 centimeters of H₂ O in reserve. Flowgeneration pressure is selectable from off to source pressure. Timecycled expiratory/inspiratory intervals can be provided.

In addition, full intermittent mandatory ventilation at all demand CPAPvalues to 30 centimeters of H₂ O can be provided. Ventilatoryfrequencies with selectable IE ratios from to 150 to 600 cycles perminute can be obtained. Intrapulmonary percussive ventilation forendobronchial secretion control to 150 cycles per minute can beobtained.

The ventilator has been provided with a modular construction with codedquick disconnect assemblies which facilitate use and servicing of theventilator.

What is claimed is:
 1. In a quick disconnect assembly, a female fittinghaving a socket formed therein, a male fitting having an integralbayonet adapted to fit in said socket, cooperative sealing means carriedby said female and male fittings for forming an airtight seal betweenthe bayonet and the socket and releasable retaining means carried by oneof said fittings for retaining said fittings in engagement with eachother, said releasable retaining means being circumferential in form andhaving first and second ends, said first end having axially extendingslots therein to provide segmental lips, said first end being providedwith an inwardly annular extending lip, said female fitting beingprovided with an annular recess receiving said annular lip, said secondend having an annular shoulder, said male fitting having an annularrecess adapted to receive said annular shoulder, said male fitting beingprovided with an inclined camming surface for camming said annularshoulder carried by said segmental lips outwardly during movement of themale fitting into the female fitting to expand said first end of thereleasable retaining means to clear said inclined camming surface and todrop into the annular recess provided on the male fitting to provide thesole means independent of forces created by the sealing means forretaining said male fitting in engagement with the female fitting, saidmale fitting and said annular shoulder of retaining means havingcooperative surfaces whereby when said male fitting is pulled away fromsaid female fitting said segmental lips are cammed outwardly to permit aquick disconnect between the male and female fittings.
 2. An assembly asin claim 1 wherein said slots are generally U-shaped.
 3. An assembly asin claim 1 wherein said slots are generally V-shaped.